text: So, Dijkstra’s Algorithm is used to find the shortest distance between the source node and the target node. Project description Release history Download files Project links. Finding the source code for built-in Python functions? This cryptosystem is based on the difficulty of finding discrete logarithm in a cyclic group that is even if we know g a and g k, it is extremely difficult to compute g ak. Wikipedia helped me understand, #I needed to test potential primitive roots multiplicative order. d[i] = z[i]h^y (mod p), # where y is chosen randomly, 0 <= y < p, #The decryption module decrypt() reads each pair of integers from Ciphertext and converts. performance of ElGamal algorithm, and the security risks existing in the traditional ElGamal digital signature algorithm are discussed from four aspects. A library written in Java and C# for crypt,encrypt and generate key pairs using the ElGamal algorithm. Ford-Fulkerson Algorithm The following is simple idea of Ford-Fulkerson algorithm: 1) Start with initial flow as 0. Using elgamal: Install elgamal by downloading elgamal.py and placing it in your module search path. Navigation. License: MIT License. I am still flexible as to the best algorithm to use, however, have identified VAR, LSTM and Facebook Prophet. Bring machine intelligence to your app with our algorithmic functions as a service API. ... du code fiscal des États-Unis. ElGamal encryption is an public-key cryptosystem. These operations are out of scope of this article. ElGamal Digital Signature by seun_sustio. These operations are out of scope of this article. You can see that all in-built functions start with builtin_, for … We run a loop while there is an augmenting path. ElGamal Encryption Algorithm. Platform technical documentation Events. Python 2.x. The Digital Signature Algorithm (DSA) is a variant of the ElGamal signature scheme, which should not be confused with ElGamal encryption. USE:  Hybrid cryptosystem uses this algorithm. 68 Le manège des chevaux . More than 50 million people use GitHub to discover, fork, and contribute to over 100 million projects. tests if num is prime, #if a is not relatively prime to n, n is composite, #declares n prime if jacobi(a, n) is congruent to a^((n-1)/2) mod n, #if there have been t iterations without failure, num is believed to be prime, #if a = b mod n, jacobi(a, n) = jacobi( b, n ). Category: 加密解密 Visual C++: Download: 加密解密算法+源代码+C Size： 385.14 kB; ElGamal.rar Size： 13.23 kB; FavoriteFavorite Preview code View comments: Description. Homepage Statistics. For an uni assignment I have been giving the task of making my own rotating algorithm in python. Download ElGamal Library for free. Loading... Close. Files for elgamal, version 0.0.5; Filename, size File type Python version Upload date Hashes; Filename, size elgamal-0.0.5-py3-none-any.whl (3.3 kB) File type Wheel Python version py3 Upload date Aug 11, 2020 Hashes View Before making this change I tried to find a 200 bit prime with confidence 100. Soundex is a phonetic algorithm, assigning values to names so that they can be compared for similarity of pronounciation. If we assume that p is a decimal prime of at least 160 bits, and p-1 has a large prime factor, and g is the generator of Z_p^*, and y \in Z_p^*. Code Issues Pull requests A Platform for Robust Threshold Cryptography based on Asynchronous Publicly Verifiable Secret Sharing with Tunable Security . The encryption procedure is implemented in encrypt(). Active 7 years, 3 months ago. It uses asymmetric key encryption for communicating between two parties and encrypting the message. Given a graph and a source vertex in the graph, find the shortest paths from source to all vertices in the given graph. Meta. Elgamal Encryption Algorithm has three parts. This asymmetric-key encryption cryptography is on the basis of the difficulty of finding discrete logarithm in a cyclic group that means we know g^a and g^k, computes g^ak. A. The algorithm. Following is the implementation of ElGamal encryption algorithm in C. L'algorithme DSA du NIST est basé sur ElGamal. But I did not receive the right message when I encrypted and, #decrypted it, despite having checked my encrypt and decrypt modules many times. MLOps Product Pricing Learn Resources. Idea of ElGamal cryptosystem The algorithm found at, #http://modular.math.washington.edu/edu/2007/spring/ent/ent-html/node31.html, #After implementing the Solovay-Strassen primality test I found it was difficult to compute 100, #bit primes even with probability 1/2. In this article, we’ll look at a surprisingly simple way to get started with face recognition using Home » Source Code » Elgamal encryption algorithm. Requires: Python >=3.6 Maintainers Sidq Classifiers. Bonjour à toutes et à tous, Nouveau petit jeu en python3. #K1 and K2 are written to files named K1 and K2. ElGamal Digital Signature by seun_sustio. Free source code and tutorials for Software developers and Architects. This is a pure Python implementation of the rsync algorithm. Here, I will include the introduction, uses, algorithm, and code in Python for Elgamal Encryption Algorithm. #them back to encoded integers. I don't know where they implement the sort() method, or what the formatting to the interpreter is, but it's got to be in there somewhere, and I bet it's implemented in C for speed concerns. This is my code so far. A Python implementation of Elgamal algorithm: encryption, decryption and signature generation and verification ctf-tools elgamal crypto-challenges elgamal-encryption Updated May 1, 2020 Elgamal Cryptography Codes and Scripts Downloads Free. # computes the greatest common denominator of a and b. assumes a > b, #solovay-strassen primality test. Key generation. Cannot retrieve contributors at this time, #Implementation of the ElGamal Cryptosystem, #Author: Ryan Riddle (ryan.riddle@uky.edu), #This python program implements the ElGamal cryptosystem. Elgamal algorithm PHP code [closed] Ask Question Asked 7 years, 3 months ago. I used a stripped-down version of the Extended Euclidean Algorithm to make it. 2 additif Algorithme de chiffrement ElGamal; 6 Différence entre l'engagement de Pedersen et l'engagement basé sur ElGamal; 1 La clé privée est-elle statique ou variable dans l'algorithme elgamal? The program is capable of both: #encrypting and decrypting a message. 3) Return flow. #I knew that encoding and decoding were implemented correctly because I could encode and decode a message, #and get the message I had started with. – Chris Lutz Oct 4 '09 at 20:54 elgamal encryption algorithm. OSI Approved :: MIT License Operating System. Mewar University NH - 79 Gangrar,(Rajasthan) - 312901 Ph. Download converting algorithm to code for free. Elgamal Algorithm Codes and Scripts Downloads Free. Viewed 1k times 0. It was proposed in 1984 and is also a double-key cryptosystem, which can be used for both encryption and digital signature. Before examining the NIST Digital Signature standard, it will be helpful to under- stand the ElGamal and Schnorr signature schemes. It was proposed in 1984 and is also a double-key cryptosystem, which can be used for both encryption and digital signature. ElGamal encryption consists of three components: the key generator, the encryption algorithm, and the decryption algorithm. It uses asymmetric key encryption for communicating between two parties and encrypting the message. These bytes are written to the file. We suggest to go through very simple explanation given on Wikipedia for detailed explanation. It is used for public-key cryptography and is based on the Diffie-Hellman key exchange. This cryptosystem is based on the difficulty of finding discrete logarithm in a cyclic group that is even if we know g a and g k, it is extremely difficult to compute g ak.. By Code Python. 空白3 2015-04-08 06:18:42: View(s): Download(s): 2: Point (s): 1 Rate: 0.0. egrsa compare time of process between rsa and elgamal algorithm used to encryption and digital signature. This is an evolutionary algorithm that returns a random list of prime numbers. Elgamal. Contoh yang dibahas kali ini adalah mengenai enkripsi dan dekripsi dari sebuah kalimat. Author: Sidq. Remove all; Disconnect; The next video is … Au pire ajoute "if 1:" à la première ligne pour forcer l'indentation. ElGamal Encryption Algorithm in Python. Elgamal’s Algorithm in Cryptography Rashmi Singh, Shiv Kumar (M.Tech.) Contribute to vkkhare/elgamal development by creating an account on GitHub. Quand tu as copié le code source tu l'as copié avec des esoaces devant toutes les lignes, python te dit donc que l'indentation est mauvaise. The probability that p is actually prime is 1-(2^-t), # g is the square of a primitive root mod p, # h = g^x mod p; x is randomly chosen, 1 <= x < p, #h is computed using fast modular exponentiation, implemented as modexp( base, exp, modulus ). No Tags Language. Metrics. I went to the web again to read over the description of the Solovay-Strassen primality test, #and realized jacobi(a, n) should be congruent to modexp(a, (n-1)/2, n) mod n. I had only been checking, #that they were equal. #encrypting and decrypting a message. Watch Queue Queue. import sys sys.path To use do. #Next the program encodes the bytes of the message into integers z[i] < p. #The module for this is named encode() and is described further where it is implemented. It is used for public-key cryptography and is based on the Diffie-Hellman key exchange. # c[i] = g^y (mod p). Of course, one can come up with home-brewed 10-liner of extended Euclidean algorithm, but why reinvent the wheel.. For example, Java's BigInteger has … It uses asymmetric key encryption for communicating between two parties and encrypting the message. ElGamal encryption can be defined over any cyclic group G {\displaystyle G} , like multiplicative group of integers modulo n . The A* search algorithm is an extension of Dijkstra's algorithm useful for finding the lowest cost path between two nodes (aka vertices) of a graph. Elgamal Algorithm Codes and Scripts Downloads Free. #After the message has been encoded into integers, the integers are encrypted and written, #to a file, Ciphertext. We suggest to go through very simple explanation given on Wikipedia for detailed explanation. You probably, intuitively, used the insertion sort algorithm. ElGamal encryption is an public-key cryptosystem. EDIT: Note, this code is not intended for actual production-grade encryption. 2) While there is a augmenting path from source to sink. I quickly figured out that when, #performing integer division on negative numbers, the result is rounded down rather than toward, #Understanding the definition of primitive roots was not enough to find one efficiently. The security of the ElGamal algorithm is based on the difficulty of solving the discrete logarithm problem. ElGamal Encryption Algorithm Last Updated: 16-11-2018 . Hybrid Cryptosystem of Hill Cipher 4x4 Algorithm and Elliptic Curve ElGamal Algorithm on Digital Image Security. After doing this. Recall from Chapter 10, that the ElGamal encryption scheme is designed to enable encryption by a user’s public key with decryption by the user’s private key. Elgamal encryption algorithm. It is implemented as follows: #The decode() module takes the integers produced from the decryption module and separates, #them into the bytes received in the initial message. ElGamal algorithm is used in encryption and decryption which is mainly considered for its capability to make the key predictions extremely tough. Elgamal In Maple Codes and Scripts Downloads Free. For this post I will write an implementation in Python. Download ElGamal Library for free. The key generator works as follows: Alice generates an efficient description of a multiplicative cyclic group of order with generator.See below for a discussion on the required properties of this group. It works. Search. This project aims at developing an application that converts the given algorithm into a code with main emphasis on the parallel algorithms and developing multi-threaded and efficient code for the given algorithm. At execution the user will be prompted for three things: # 1) a number n which specifies the length of the prime to be generated, # 2) a number t which specifies the desired confidence that the generated prime, # 3) the name of a file that contains the message he wishes to encrypt and decrypt, #After the user has provided the necessary information the program will generate a pair, #of keys (K1, K2) used for encryption and decryption. Download the source code to the Python interpreter. The algorithm [edit | edit source]. I had, #search the web to understand how primitive roots can be found. Permissions. ElGamal encryption is an public-key cryptosystem. ELGAMAL DIGITAL SIGNATURE SCHEME. The ciphertext (c1,c2) is sent to Alice by Bob. There's some bug in the decryption which I'm unable to solve. elgamal java free download. Python SQL Tools Visual Basic & VB.NET XML: New Code; Vue Injector 3.3: Spectrum Analyzer pro Live 2019 : Devart Excel Add-in for HubSpot 2.1: RentALLScript - Airbnb clone 2.2: SuiteCRM Theme Customization 7.11.6: iScripts NetMenus 3.1: iScripts EasyIndex 2.2: iScripts EasySnaps 2.0: Australia MyPost shipping For Magento 2 1.0.0: Australia Post eParcel For Magento 1.1.1: Source Control for … This is an evolutionary algorithm that returns a random list of prime numbers. Key generation [edit | edit source]. ElGamal¶ Overview¶ The security of the ElGamal algorithm is based on the difficulty of solving the discrete logarithm problem. Following is the implementation of ElGamal encryption algorithm in C. egrsa compare time of process between rsa and elgamal algorithm used to encryption and digital signature. A library written in Java and C# for crypt,encrypt and generate key pairs using the ElGamal algorithm. #finding prime numbers with confidence > 2, #I found it took a long time to test primes with a large number of bits with confidence greater than, #two. ; Choose an integer randomly from {, …, −}. Ecommerce Pricing Algorithm with a GUI Online Product / SAAS Pricing Algorithm Code pulls comparable pricing data from online stores. It doesn’t take much Case studies, videos, and reports Docs. The program is capable of both. GitHub is where people build software. I met with Professor Klapper to discuss this problem and he, #suggested I quit running the program on UK's shared "multilab" and I speed up my Jacobi algorithm, #by using branches to find powers of -1 rather than actually exponentiating them. a number y = invmod(x, p) such that x*y == 1 (mod p)?Google doesn't seem to give any good hints on this. If you don't know your module search path, fire up a python console and run. #The first problem I encountered was in implementing the fast modular exponentiator, modexp(). 9694430530 Email_id: rashmikamal011@gmail.com Abstract— Cryptography, over the ages, has been an art practiced by many who have devised ad hoc techniques to meet some of the information security requirements. elgamal encryption with matlab Search and download elgamal encryption with matlab open source project / source codes from CodeForge.com This is a pure Python implementation of the rsync algorithm. As far as I can see, even though it's a widely known algorithm, there seems to be only two free implementations: libgcrypt supports Elgamal encryption; pycrypt has Elgamal; OpenSSL, beecrypt, Nettle do not implement Elgamal. Elgamal encryption algorithm Search and download Elgamal encryption algorithm open source project / source codes from CodeForge.com Public Parameter: A trusted third party publishes a large prime number p and a generator g. In this algorithm, someone can know your message only when he/she knows the value of a. The approach that Dijkstra’s Algorithm follows is known as the Greedy Approach. Here is some french text: Maître Corbeau, sur un arbre perché. Here, I will include the introduction, uses, algorithm, and code in Python for Elgamal Encryption Algorithm. Elgamal’s Algorithm in Cryptography Rashmi Singh, Shiv Kumar (M.Tech.) # Smart-Boxes_Python-AI Smart Boxes, Python/Pygame AI Project with Genetic Algorithm by Burak Unutmaz INTRODUCTION * This is my first swing at the Genetic Algorithm… For your project s to p-2 instead of -1 in the decryption algorithm does standard. 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# Induction with multiple variables

Let the function g : R $\rightarrow$ R satisfy $g(xy) = x \cdot g(y) +y \cdot g(x)$ for all real numbers x and y.

Prove $g(u^n) = nu^{n-1}g(u)$, for all positive integers $n$ and all real numbers $u$.

the Inductive step for me is a bit tricky, the base case is straightforward:

$g(1^{1})$ = $1\cdot 1^{0}\cdot g(1)$

$g(1) = g(1)$

Now, I believe I have a fundamental misunderstanding of what induction looks like. Of course in this case it means to try and compute $u+1$ and $n+1$, but plugging it in and doing all the algebra isn't working for me.

Any hints, tips, suggestions?

Edit:

Going off of what voldemort said, $u$ is fixed and we're only trying to prove the induction step for n+1. I get the following:

$g(u^{n+1}) = (n+1)\cdot u^n\cdot g(u)$

However, I'm unsure of how to algebraically deal with exponents in side functions.

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Tom: you do not need to prove it for $u+1$. Fix $u$ and prove this for all $n$ by using induction. This will show that the result holds for all real numbers $u$. – voldemort Feb 11 '14 at 19:04
It's not clear to me what you mean by "perform induction." Induction would require you to be trying to either prove or define something. You haven't really given us a statement you are trying to prove. – Thomas Andrews Feb 11 '14 at 19:04
Thomas, I'm trying to prove the equation I listed. – Benji_Bombadill Feb 11 '14 at 19:07
Voldy, I'll trying to redo the math. – Benji_Bombadill Feb 11 '14 at 19:08
It seems that there is really only one function involved. Replace every $g$ by $f$ in your question maybe? – Christoph Feb 11 '14 at 19:24

Let $f:\mathbb R\to\mathbb R$ be a function satisfying $f(xy)=x\cdot f(y)+f(x)\cdot y$ for all $x,y\in\mathbb R$.

Claim: For all $n\in\mathbb N$ and $u\in\mathbb R$ we have $f(u^n) = nu^{n-1} f(u)$.

Proof. Let $u\in\mathbb R$ be any real number. Proceed by induction on $n$.

For $n=1$ the claim is $$f(u^1) = 1\cdot u^0 f(u),$$ which is true, since $u^0=1$ and $u^1=u$.

Now let the claim hold for a fixed $n\in\mathbb N$, then $$f(u^{n+1}) = f(u^n u) = f(u^n) u + u^n f(u) = nu^{n-1} f(u) u + u^n f(u) = (n+1)u^n f(u)$$ as desired. $\square$

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when write $f(u^n u) = f(u^n) u + u^n f(u)$, is this just a known function operation? – Benji_Bombadill Feb 11 '14 at 20:00
No, this is the known property of $f$, namely $f(xy) = f(x)\cdot y + x\cdot f(y)$, applied for $x=u^n$, $y=u$. – Christoph Feb 11 '14 at 20:02
Aww. Right in front of my face. – Benji_Bombadill Feb 11 '14 at 20:06

You cannot prove a statement about all $u\in\mathbb R$ by induction (well, some nitpickers might find ways, but ignore that). Proof by induction is for $\mathbb N$, not $\mathbb R$, because induction is the very essence of the Peano axioms - for the natural numbers. So (as already has been said in the comments), let your statement $P(n)$ be:

$P(n)$: For all $u\in\mathbb R$ we have $g(u^n)=nu^{n-1}f(u)$

Then show $P(1)$, i.e.:

For all $u\in\mathbb R$ we have $g(u)=f(u)$.

and show $P(n)\implies P(n+1)$. (However, I don't know how as you do not mention any specific properties of $g$ and $f$ as given)

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Alright, let me add to the problem. – Benji_Bombadill Feb 11 '14 at 19:19
+1 for you cannot prove a statement about the reals using induction. However, I would not back off and say it is possible because it is not. – kleineg Feb 11 '14 at 19:21
Voldemort pointed out that u (the reals) is fixed. – Benji_Bombadill Feb 11 '14 at 19:24
@kleineg Some weird theorem might be provable for $u\in[0,1]$ and then with induction steps $u\to u\pm 1$. – Hagen von Eitzen Feb 11 '14 at 21:01

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# Should homework questions disclose that they are homework questions?

The FAQ on "How do I ask and answer homework questions?" had an accepted top community wiki answer from the beginning (Oct 23 '08) that said:

• Admit that the question is homework. Trying to hide it will just get the question closed faster. Do not use a “homework” tag, but mention it in the question text if relevant (you can structure your question this way: “How can I do …? I'm trying to do this as part of … which is a homework problem. This is my attempt so far: …”).

This paragraph was removed in r8 and promptly restored by the person who wrote the answer originally. This was removed again months later when a different editor removed that paragraph along with another edit and again restored by the original author. The same editor pair removed and restored the content an additional time, and then another editor removed it. Other edits followed, with discussion focused on other points, like if the FAQ content should avoid summarizing points from elsewhere on meta because they could be found elsewhere. This paragraph got removed without substantive discussion on this point.

When it was restored (because there had not been substantive discussion or consensus on this point), it was quickly removed with the edit comment

There is no such rule. We do not create new rules in community wikis. We add them if they exist. If you think there should be such a rule please start a discussion first.

So apparently we remove longstanding rules without discussion, even if they have stood in the FAQ on the topic for years and resisted prior removal, but we don't restore content that was disturbed during unrelated editing without being accused of creating new rules.

In later discussion on a different meta topic, a user who disagreed with that point repeatedly claimed:

You can see that there has been a long consensus that whether or not a question is related to a homework problem is irrelevant to the question...whether homework questions need to be marked as such has been discussed to death and the consensus came to be that homework questions should be treated as any other type of question, and not marked as such.

This meta question is intended to serve as a focal point for that discussion that has allegedly long happened but could not be linked to, beyond discussion of using a tag which was already linked to in the original paragraph giving a different rule about admitting the question is homework.

Should homework questions admit that they are homework?

Note: By asking this question, I am not intending to imply a position either way, but I am intending to start the discussion instead of having to argue about whether or not such a discussion exists and has long ago reached the opposite conclusion to the one that stood for many years in the highly-upvoted FAQ for the topic, and was removed without substantive discussion on that point.

• I'm not sure how continually referring to the original author strengthens your case; it's a community wiki, so the original author has no greater say than anyone else when it comes to edits. – fbueckert Nov 8 '18 at 16:02
• Based on the tone and slant of your meta posts here, I disagree with that assertion. I think you are making a case. They don't sound at all neutral. – fbueckert Nov 8 '18 at 16:10
• Of course, it's okay to not be neutral and to have an opinion on a topic, even when starting a discussion on it. It's just that claiming you have no position and that you're being neutral falls rather flat when your posts and wording show a very clear bias to one view. Just be open about what your opinion is. People can then agree or disagree with it. It's how discussions on meta generally go. – Servy Nov 8 '18 at 16:12
• @WBT Also, you were linked to posts stating the consensus is that that doesn't belong in the question. You just didn't like them. You can't say people can't, or didn't, provide you with sources, when they both can, and did. – Servy Nov 8 '18 at 16:17
• @WBT Given that the comments are deleted, I couldn't say why no one linked to past discussions there (or even whether anyone did). Did you ask if there were discussions on the topic, given how opposed you are to it being removed? – Servy Nov 8 '18 at 16:42
• @WBT I did link you to a discussion stating that there is no need for homework questions to disclosed that they're homework questions, and it had a duplicate it was linked to, and several other questions in comments and in the answer, all on the topic. – Servy Nov 8 '18 at 16:48
• @WBT The numerous discussions linked all say that whether a question is a homework problem or not is irrelevant, and doesn't belong in the question. They weren't saying that there should be no homework tag but that every single homework question must say, in the question, that it's homework. They said that the homework tag doesn't exist because questions should not be indicating whether they're homework or not because it's just noise. – Servy Nov 8 '18 at 16:57
• You keep saying things like "numerous discussions linked" and claim a longstanding overwhelming consensus. Please actually link to the discussions you're claiming, and not discussions about tagging, in your next comment. The point in the FAQ acknowledged the discussion about not tagging and claimed a need for disclosure even considering that. Show me a discussion that focuses on disclosure specifically, if you think this is a duplicate. – WBT Nov 8 '18 at 17:01
• @WBT I linked you to it in your previous meta post, you've been given links in the answer. You can't type "homework" in the search bar without finding a dozen posts on the subject. That one person kept reverting the FAQ when it was changed because that one person didn't like the well agreed on consensus doesn't make them right. – Servy Nov 8 '18 at 17:05
• @WBT I linked you to posts that specifically said that it's not appropriate for a question to state whether or not it's homework, and that it's noise. Thus, that's demonstrating that the statement that "all homework questions must state that they are homework" is not in line with the community consensus. The questions aren't just about the homework tag. Again, they're not all saying, "Don't use the homework tag, but never forget to mention that a problem is homework". If they did, you would have a point. – Servy Nov 8 '18 at 17:17
• @WBT That other posts also mention that the homework tag doesn't exist because it's specifically policy that homework questions shouldn't mention that they're homework doesn't make them off topic in a question about whether posts should indicate that they're homework. In fact, it makes them a dead on answer. But hey, you wanted to create yet another duplicate. Congrats. You succeeded. Surprisingly, nothing changed, and you succeeded in getting a bunch of people to repeat, exactly, what was in the numerous duplicates you saw. – Servy Nov 8 '18 at 17:18
• Good faith can only go so far. All this obstinance and pedantry on requiring a link makes it look like you're trying to push an agenda. For me, the links provided, both here and in your previous question were enough. Making a distinction between tag discussions and actual site policy is playing with semantics, and doesn't move the discussion forward at all. – fbueckert Nov 8 '18 at 17:26
• And again, all this insistence on what the author wants or does makes zero sense. Who cares!? It's literally irrelevant to the current situation. – fbueckert Nov 8 '18 at 17:28
• @WBT Apparently no one noticed. Like I've said before, the FAQs aren't kept nearly as up to date as you seem to think they should be. That, and the fact that one person who disagrees with the consensus kept rolling back changes to it when others would fix it to be in line with the community consensus. You keep saying discussion was needed to remove it but there were dozens of discussions on the topic. There wasn't one person changing established policy without it being discussed, rather it was one person reverting the changes every time someone brought it in line with established policy. – Servy Nov 8 '18 at 20:33
• @WBT Just repeating over and over again that no one has ever discussed whether or not homework questions should be marked as homework, and when you've seen multiple examples yourself, doesn't make it true. It's been proven demonstrably false, many times, that this has been discussed, and even that you knew about those discussions before duplicating it by posting this question. – Servy Nov 8 '18 at 23:10

## No, they shouldn't.

What the answer is going to be used for is mostly noise, unless it's directly related to the question.

We don't care if the asker works at NASA or McDonalds. It's not important if this is their first job or if they are still studying.

What matters is that questions follow the site topicality rules, are properly scoped and clearly defined.

• On a good question, stating that it arises from a homework problem is noise at best, but most likely a distraction.

• On a bad question, it's an attempt to deflect criticism and judgement with information tangential to the question's quality and topicality.

We shouldn't encourage users to put irrelevant information in their posts, and we should edit it out if we encounter noisy posts.

• I believe the contention here is the edit war and the subsequent lock on the FAQ – Suraj Rao Nov 8 '18 at 16:00
• @WBT ok.. but the question itself focused on the arguments that occured in the edit war which led me to believe otherwise – Suraj Rao Nov 8 '18 at 16:05
• @WBT I think 5 users fighting in a massive rollback war doesn't indicate a lack of consensus In the community, but rather amongst these five users (I know my number isn't necessarily accurate, but you get my point I guess) – Patrice Nov 8 '18 at 22:55
• @WBT Did I say anything about that? All I said is that five users fighting on a FAQ isn't any indication of a community consensus or LACK of that consensus. It just shows that these five users aren't aligned. As soon as you posted a question for the whole community to see, that consensus was clear, and pointed to numerous other discussions that showed that consensus. Seriously, what more do you want? You are aware that the FAQ doesn't get reviewed by the full community everytime a single thing changes in it? – Patrice Nov 9 '18 at 14:09
• @WBT There was one user constantly rolling back the content, and you. And since you claim (clearly in bad faith, but you have made the claim nonetheless) that you were just rolling it back because you think every single change to an FAQ should be rolled back unless there is a meta discussion about it, that leaves just one person constantly rolling back the changes. Given that there are dozens of meta discussions on the topic, all with very wide agreement on the topic, one person constantly rolling it back (plus you) doesn't override that. – Servy Nov 9 '18 at 14:12
• @WBT "I was accused of creating a new rule without on-point discussion" Which you did, for the record. It's not okay to edit an FAQ to suggest guidelines that aren't in line with other discussions. The FAQ isn't the place to suggest new things, as you did. Of course, the removal of the statement that homework questions must disclose that they're homework is not changing policy. It has been long and well established policy that homework questions should not disclose that they're homework. There was no need to discuss it again before changing the FAQ. – Servy Nov 9 '18 at 14:58
• @WBT I linked to numerous discussions all saying that homework questions shouldn't disclose in any way that they're homework. And that because of this, the homework tag was removed. Those numerous discussions were ally very clear, with overwhelming support, that homework questions shouldn't disclose that they're homework at all, because it's noise, and that you should remove any reference to it from the question. They're exactly on point, and demonstrate that the FAQ entry was specifically opposed to well established consensus. – Servy Nov 9 '18 at 15:01
• @WBT where did I say I claimed community consensus? You're twisting (or reimagining) what I said...Again, you seem to say the fact it was in an FAQ means it was a rule, or that it indicated community consensus. it didn't, as all the discussions Servy shared with you (and I truly don't feel like rehashing those, again) – Patrice Nov 9 '18 at 15:01
• @WBT You can't just say, "Every single discussion only talked about the tag and none of them discussed disclosure in the question," when those discussions did in fact discuss disclosure in the question, and said that it's noise. Your claim is simply not true. Mentioning that there shouldn't be a tag as well doesn't change that. – Servy Nov 9 '18 at 15:02
• I don't think it's worthwhile to continue this discussion, guys; it's clear there's not going to be any agreement. Might be best to just let it lie and lets the votes do their thing. – fbueckert Nov 9 '18 at 15:07
• @WBT You weren't suggesting new things to the FAQ by rolling back the removal of the statement that homework should be disclosed as such. You were suggesting new things with your other edits to the FAQ to add in new guidelines. Your rollback of a useful change to the FAQ to keep it in line with well established community consensus was wrong, but not the portion of your edits that was suggesting new things to the FAQ. – Servy Nov 9 '18 at 15:08
• @WBT There's one link that itself links to numerous other duplicate discussions on the topic, and you can search for dozens more that have happened over the years. You can trivially find them. I believe in your ability to search for the word "homework". You're skilled enough to do it if the five discussions linked to you aren't enough. The fact that the FAQ was wrong for several years doesn't mean no one is allowed to change it. AS you've been told, the FAQs are often not as up to date as they should be. That's not an argument for refusing to update them. – Servy Nov 9 '18 at 15:11
• People, get a chatroom. – yivi Nov 9 '18 at 15:11
• @WBT No, you were not specifically told that. And now that the comments are public again, everyone can see that you were lying by claiming that you were told no meta post should ever duplicate content found elsewhere. You were told that the content you added wrong, and you were also told that it was off topic in this post. I'll quite Tiny's relevant comment below, but it very clearly states that what you added was off topic. It said we shouldn't duplicate everything on meta in one post; it doesn't say no post should ever duplicate anything found elsewhere. – Servy Nov 9 '18 at 15:15
• GUYS, yivi's likely getting massive pings from this and indicated they'd prefer not to.... do you mind moving this to the chat, or at least the Q, so Yivi's inbox isn't flooded.... – Patrice Nov 9 '18 at 15:22

# We've been over this already.

Every question on the site needs to be on-topic. The only details that need to be included in the question are the details needed to define constraints on how the problem can be solved. Labeling a question as "homework" only makes it easier for those who already have a dislike for homework questions to simply downvote and move on with their lives in spite of the fact that the question may be otherwise acceptable on the site.

I did jump in and remove the language about the question needing to be homework. Why?

# Because it's noise!

It doesn't help you solve the problem. It doesn't help you define the problem. If the issue is that you don't necessarily like the question then we need to have a separate discussion about what questions we do and don't like here at Stack Overflow.

• It was contested...the removal of the content was reverted three times by the person who originally wrote that content. – WBT Nov 8 '18 at 16:51
• @WBT Again, who wrote it, in a community wiki, is irrelevant. – fbueckert Nov 8 '18 at 16:55
• @WBT: Unless my search-fu is weaker than normal today, the only time it was contested was by you, in a rollback that should have never been done... – Makoto Nov 8 '18 at 16:56
• @Makoto The history of revisions to this point in the FAQ post is documented above. Fbueckert: Clearly, someone cares about the identity of who's editing. – WBT Nov 8 '18 at 16:58
• @Makoto One of the rollbacks that added that statement back in was WBT, 4 were Joel Coehoorn, one was Yvette. – Servy Nov 8 '18 at 17:00
• @Servy: I was looking at revisions 17+. – Makoto Nov 8 '18 at 17:02
• @Servy and I only restored it because I perceived a lack of on-point discussion supporting removal of a point that had stood for years. My action on that point was motivated by process, with the same principle as ayhan's r24. Once this discussion settles down, I would support whichever action is consistent with the consensus reached here. – WBT Nov 8 '18 at 17:21
• On MathStackExchange I consider recommandable that homework questions be presented as such it is a straightforward helps to prevent entry-level questions to be solved with advanced techniques (i.e. a valid but unhelpful answer) and also helps making the answers useful for the original poster. On StackOverflow this seems to be a lesser problem, but I wouldn't like to see people trying to disguise questions that in the end are homework as if they weren't nor should valid questions be discouraged or hostilized. – Mefitico Nov 8 '18 at 17:31
• Your claim (if I understood it properly) is that a homework tag would raise rejection, but there are moderation tools (such as flagging comments) to keep this problem in check. And regarding dislikes I think they're pretty much fair game. – Mefitico Nov 8 '18 at 17:31
• @Mefitico: At a fundamental level, what's the difference between a homework problem and a practical problem? Remember that not only is the world of math not the same as software engineering, so too is Math Overflow not the same as Stack Overflow. – Makoto Nov 8 '18 at 17:54
• Makoto: With a practical problem, frame challenges (e.g. 'use a while loop instead of a for'; 'use the language's built-in sort() instead of implementing your own') are more helpful answers than they are on homework problems with their artificial constraints. @Mefitico doesn't seem to be claiming SO and MO are equivalent, and the comment explicitly distinguishes between the sites, but also provides the background information and reasoning for whatever it may be worth in this discussion here. – WBT Nov 8 '18 at 18:00
• In general, when programming professionally I need to achieve something which I can specify clearly once I reach "question level", and if if find a solution that works, I can often apply it without understanding it (though I'll usually take my time to understand the issue later). If I'm doing homework, then the understanding is the main goal and maybe a snippet of working code does not teach me what I need to know, the answer would benefit from more explanation and some guesswork on what are the shortcomings on my comprehension of the topic (my question itself may should be put into question). – Mefitico Nov 8 '18 at 18:06
• Also, I was a preparatory course teaching assistant in the past (for math, physics, chemistry). Though "the answer" to the same question would always be the same, I would widely change my answer method and steps based on the student (do I know he comprehends the topic but missed a detail? Do I believe he actually needs a lecture on the topic before the question is approached? Does he know well the pre-requisites for a given topic?). Though indeed I was never a programming teacher. – Mefitico Nov 8 '18 at 18:10

If the question is using material from someone other than the poster, it needs to properly reference it. This is just the regular plagiarism policy.

If the question has unusual constraints (e.g. "must use a for loop"), the reason why should be mentioned. If you don't mention this from the start, you'll probably be asked about it, since it's a key piece of information in deciding if a "frame challenge" answer (e.g. "use this while loop instead") would be acceptable.

I can't think of any other situation where you'd need to disclose the fact you're asking about homework (at least on Stack Overflow). In the end, it's just evaluated on whether it's a good question or a bad one and I think we'd all rather someone focus on the steps to making the question good.

Disclosing that a question is homework helps potential answerers or commenters understand artificial constraints that the question presents, e.g. not being able to use a language's built-in sort() function. Therefore, in questions with these sorts of artificial constraints, it can be helpful to explain the reasoning behind them.

• "understand artificial constraints that the question presents, e.g. not being able to use a language's built-in sort() " I would advise to just mention those constraints explicitly, possibly even including that it's, as already mentioned, an artificially unavoidable constraint. But hey, this still is not exactly, what was in that particular guideline: admit that it's homework suggests that one should always make it clear to everyone else that it is homework, even when that information is irrelevant. – E_net4 on strike Nov 8 '18 at 16:24
• Unless something is physically impossible in software, every constraint that exists is artificial. You'd be surprised how often real-world problems get mistaken for homework problems. – Makoto Nov 8 '18 at 16:24
• @WBT So why not let people come to their own decisions, instead of saying "People will probably say this, so let me remind them that there are other options."? Does that not seem like something someone with a particular bias would do? – Ethan Field Nov 8 '18 at 16:46
• @EthanField The well-studied phenomena of groupthink leads people to overlook other options once they have found one that seems to have merit. Balanced discussions often require someone stepping into the role of pointing out other options even if they are not personally convinced that those alternatives are the best option. – WBT Nov 8 '18 at 16:50
• @EthanField Also, I didn't guess at which point "people will probably say" first. I waited and when I saw only one side presented and starting to gain upvotes, I put in the other so they could both be considered. As stated above, had this point been posted and started to gather votes first, I would have posted an answer like one of the others ("Every question on the site needs to be on-topic. The only details that need to be included in the question are the details needed to define constraints on how the problem can be solved. Unless it's relevant to defining the question, it's noise.") – WBT Nov 8 '18 at 16:57
• @Ethan Field: Re-stating here an opinion others have made elsewhere does not equate to holding a personal stake in it. You can disagree with an opinion but respect it enough to consider it relevant to the conversation. It probably befits this answer to be a community wiki to drive home the point that WBT themself doesn't subscribe to the stated opinion. – BoltClock Nov 8 '18 at 17:44


text:
Comparison of Rational Numbers
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Among the positive rational numbers with the same denominator, the number with the greatest numerator is the largest. It is easy to compare the rational numbers with same denominators. e.g. $\frac{\text{28}}{\text{30}}$ > $\frac{\text{26}}{\text{30}}$ > $\frac{\text{21}}{\text{30}}$. A negative rational number is to the left of zero whereas a positive rational number is to the right of zero on a number line. So, a positive rational number is always greater than a negative rational number. To compare two negative rational numbers with the same denominator, their numerators are compared ignoring the minus sign. The number with the greatest numerator is the smallest. e.g. – < – ; – $\frac{\text{6}}{\text{7}}$ < –  To compare rational numbers with different denominators, they are converted into equivalent rational numbers with the same denominator, which is equal to the LCM of their denominators. There are unlimited number of rational numbers between two rational numbers. To find a rational number between the given rational numbers, they are converted to rational numbers with same denominators.

#### Summary

Among the positive rational numbers with the same denominator, the number with the greatest numerator is the largest. It is easy to compare the rational numbers with same denominators. e.g. $\frac{\text{28}}{\text{30}}$ > $\frac{\text{26}}{\text{30}}$ > $\frac{\text{21}}{\text{30}}$. A negative rational number is to the left of zero whereas a positive rational number is to the right of zero on a number line. So, a positive rational number is always greater than a negative rational number. To compare two negative rational numbers with the same denominator, their numerators are compared ignoring the minus sign. The number with the greatest numerator is the smallest. e.g. – < – ; – $\frac{\text{6}}{\text{7}}$ < –  To compare rational numbers with different denominators, they are converted into equivalent rational numbers with the same denominator, which is equal to the LCM of their denominators. There are unlimited number of rational numbers between two rational numbers. To find a rational number between the given rational numbers, they are converted to rational numbers with same denominators.

#### References

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text:
C_D
Posts: 62
Joined: Mon May 11, 2015 3:27 am
Location: New Zealand

Just as a quick test I had a bit of a google and a search around the forum and I can't find a place where the instructions for flashing the bootloader are stated. There are some mentions in threads, and a few hints in the youtube video, but there doesnt seem to be a 'go to' set of instructions.

I think the instructions for flashing the generic bootloader (or a link to them) probably should be on the main page of the git repo, or in the wiki (which looks like is under way). And there probably should be a link across from the Arduino_STM32 git repo as well depending on which bit a new user stumbles into first.

I'm not sure what the procedure is for other boards (I know there's a few variations) but for my 'blue pill' board and working under windows the instructions are something like:

Set BOOT0 high and BOOT1 low.
Press reset.
Open a command window and run:
Arduino_STM32\tools\win\stm32flash.exe -w [path\to\generic_boot20_pc13.bin] [COM_PORT]

RogerClark
Posts: 7546
Joined: Mon Apr 27, 2015 10:36 am
Location: Melbourne, Australia
Contact:

@C_D

There is already a page in the wiki about the stm32duino bootloader which includes how to flash it

I think the problem is that the forum is a forum and not necessarily a good way to present information.

I could put a start here section, but I can't guarantee that people will read it.

I probably need to do an accompanying website which just contains blog style postings, as part of the same domain and move this to forum.stm32duino.com but I don't really have time to do that at the moment, as there are still quite a few technical issues that need to be resolved e.g. STM32Flash doesnt work for FDTI adaptors on OSX, so I need to fix this so that those OSX users can flash the bootloader

Ideally, we could flash the bootloader via the menu in the IDE, but there is precious little documentation on how to set this up.
I think we need a file called programmers.txt, but I'm not sure what would go in it, in order for the burn bootloader to work, additionally, we'd need a way to select which bootloader to use, as there are lots of them.

I will email the IDE developers mailing list to see if anyone knows where I can find some docs about this

C_D
Posts: 62
Joined: Mon May 11, 2015 3:27 am
Location: New Zealand

Hey, there it is!

Somehow I failed to find that page when I searched. Does google search inside the git wikis? I guess its not going to come up in search results anyway until people start finding it and getting some traffic there.

RogerClark
Posts: 7546
Joined: Mon Apr 27, 2015 10:36 am
Location: Melbourne, Australia
Contact:

@C_D

I honestly don't remember writing it, but it was there when I looked, so I must have written it

I also wrote quite a detailed readme in the stm32duino-bootloader repo, but that was for people who wanted to rebuild it or add new build targets eg. boards with LEDs and buttons on different pins

mrburnette
Posts: 2049
Joined: Mon Apr 27, 2015 12:50 pm
Location: Greater Atlanta
Contact:

C_D wrote:Hey, there it is!

Somehow I failed to find that page when I searched. Does google search inside the git wikis? I guess its not going to come up in search results anyway until people start finding it and getting some traffic there.

YES, you can search directly from Google for the STM32 information, in this case Roger's github site:
I probably need to do an accompanying website which just contains blog style postings, as part of the same domain and move this to forum.stm32duino.com but I don't really have time to do that at the moment, as there are still quite a few technical issues that need to be resolved e.g. STM32Flash doesnt work for FDTI adaptors on OSX, so I need to fix this so that those OSX users can flash the bootloader
Roger, I think this may be a poor use of your time. We have the forum, we have your github account, we have the Wiki. Another website, IMO, is only going to cause discourse in trying to keep sites coordinated with the same information.

Just a bit of recent history for everyone:
Sometime during the 9 months of life this project has lived, a statement was made about the numerous boards and the Arduino support of same. The summary of this discussion was that this STM32 initiative was a corroborative endeavor - a core set of boards would be built from those within the group and new boards would be introduced but that labor intensive tasks such as pin-mappings would require the purchaser of said new board(s) to work to complete the effort by modifying the closest working board pin-maps.

I know that many members here have dedicated a lots of time to get us where we are today. However, as the forum grows, we need to have everyone understand that the work effort must be shared among us all. While I personally believe Roger is a superhuman individual, he is still only one person and cannot undertake every need. If we need more documentation, then please feel free to author same; even if you are a newbie, your write-up and point of view may be just what is needed to keep the documentation simple and easy to understand. But, read on...

I think what most people really want are examples that run. Victor_pv, Strawberrymaker, madias and many others have posted within the forum excellent examples. I did a small series for beginners which found it way into the Examples of the ZIP download. We have examples for ILI9341, BMP180, OLED, etc. :mainstream stuff many can utilize. But there can never be too many examples, so for those members that have been reading and following along, feel free to add your projects - there is a Projects section in the Forum.

Ray
My stuff: http://www.hackster.io/rayburne

hmeijdam
Posts: 3
Joined: Tue Dec 01, 2015 9:54 pm

It took me a couple of hours to figure this out as I have the STLink dongle hooked up to a generic STM32F103C...

I first attempted to use the STM32 STLINK UTility that comes with the STLink driver from STM. That tool connected to my STM32 just fine, and I could also load the binary bootloader file for my board in it (mine has the led on PC13).
https://github.com/rogerclarkmelbourne/ ... 1/binaries

But as soon as I tried to erase the chip or load something I got an error "The elf loader file is not accessible".
By accident I saw a post where stm32flash.exe was mentioned, and once I found that was stored in the ARDUINO_STM32-master\tools\win folder I also saw the "stlink_upload.bat" command file.
For some reason the dos box command "stlink_upload.bat generic_boot20_pc13.bin" did not work, but after I shortened the filename to bootl.bin and I just entered the command " stlink\ST-LINK_CLI.exe -c SWD -P bootl.bin 0x8000000 -Rst -Run "

Bingo !!

The DFU driver was installed and now I have a perfect working bootloader on my STM32F103C...

Loads sketches faster and I have serial communication.

Test sketch that I used

Code: Select all

void setup() {
//  Serial.begin(9600); // Uncomment if needed by boards using hardware serial via a USB to Serial adaptor
pinMode(PC13, OUTPUT);
}

void loop() {
digitalWrite(PC13, LOW); // set the LED on
Serial.println("Hello from STM32F103C8T6, I am alive and kicking !!!");
delay(25);
digitalWrite(PC13, HIGH); // set the LED off
delay(1000);
}

Very happy so far.

RogerClark
Posts: 7546
Joined: Mon Apr 27, 2015 10:36 am
Location: Melbourne, Australia
Contact:

Hi

FYI.

Those Windows bat files are used by the IDE and expect to be passed various parameters, hence why it didnt work when you just passed the file name.

Btw

I have no idea why STMs Stlink program didnt work. But thats outside of our control.

Anyway, Im glad its now working for you

zmemw16
Posts: 1602
Joined: Wed Jul 08, 2015 2:09 pm
Location: St Annes, Lancs,UK

as an almost non-non-non-windows user i ain't doing this
what might be seriously useful would be an idiots guide to generating a PR and what you need in it.

thinking very hard as to what i actually do 'do' in XP, aaahhh - reading a book via kindle cloud, it's easier than flitting from kindle to screen and back.

anyone got a BSOD for no arguments on command line? defaults to a usage output line.

googling 'batch file argument count' yields

http://www.testdeveloper.com/2010/09/26 ... nt-page-1/

and it has this as code

Code: Select all

@echo off

set _exitStatus=0
set _argcActual=0
set _argcExpected=2

echo.

for %%i in (%*) do set /A _argcActual+=1

if %_argcActual% NEQ %_argcExpected% (

set _exitStatus=1

goto:_EOF
)

goto:_EOF

:_ShowUsage

echo [USAGE]: %~1 arg1 arg2

echo.

if NOT "%~2" == "" (

echo %~2

echo.
)

goto:eof

:_EOF

echo The exit status is %_exitStatus%.

echo.

cmd /c exit %_exitStatus%

mrburnette
Posts: 2049
Joined: Mon Apr 27, 2015 12:50 pm
Location: Greater Atlanta
Contact:


text:
# Generalization of Killing form

I am reading Knapp's book "Lie groups beyond introduction". On page 369, he has described the following. Let $$\mathfrak g$$ be a real semisimple Lie algebra. Suppose $$\theta\colon\mathfrak g\to \mathfrak g$$ is a Cartan involution. Let $$B$$ be a nondegenerate symmetric bilinear form on $$\mathfrak g$$ which is $$\theta$$-invariant and $$B_\theta(X,Y):=-B(X,\theta Y)$$ is positive definite. Let $$\mathfrak g=\mathfrak k\oplus\mathfrak p$$ be the Cartan decomposition of $$\mathfrak g$$ where $$\mathfrak k$$ and $$\mathfrak p$$ are eigenspaces of $$\theta$$ corresponding to eigenvalues $$1$$ and $$-1$$ respectively. Then clearly, $$\mathfrak k\oplus i\mathfrak p$$ is a compact real form of $$\mathfrak g^{\mathbb C}$$ (complexification of $$\mathfrak g).$$ Hence $$B$$ is negative definite on a maximal abelian subspace of $$\mathfrak k\oplus i\mathfrak p$$. I understood up to this point. Now Knapp argues that from above one can conclude that for any Cartan subalgebra of $$\mathfrak g^{\mathbb C}$$, $$B$$ is positive definite on the real subspace where all the roots are real valued. I do not understand how to get this. However, if $$B$$ is in particular the Cartan-Killing form then I can check by hand that this claim holds. Can someone please help me out?

• I don't understand your question. Please check for typos. I've consulted Knapp's book and page 369 in my edition (from 1996) is devoted to exercies. Which edition are you using? Jun 15 '20 at 13:26
• @Vit. I am reading the second edition. Please help me out if you can. I am struggling to understand this point. As far as typos are concerned, I think that is alright. Jun 15 '20 at 13:34
• No, it's not all right. What do you mean by "all roots are real values"? Jun 15 '20 at 13:45
• @Vit. Corrected. Jun 15 '20 at 15:03

According to theorem 2.15, all Cartan subalgebras of a complex semi-simple Lie algebras are conjugated. I.e. there exists $$\alpha \in \mathrm{Inn}(\mathfrak{g})$$ such that $$\mathfrak{h}_1 = \alpha(\mathfrak{h}_2).$$ Since any invariant form $$B$$ is also invariant with respect to the group of inner automorphisms (sorry, I don't know if or where Knapp proves this), it follows that any positivity property is preserved for corresponding real forms of all Cartan subalgebras.


text:
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## How to toggle between two custom fields in the add-in & # 39; WC Product Field Group & # 39; WordPress woocommerce?

I have a full suit that adapts the WordPress website and I use it with the woocommerce plugin. I need 2 groups of custom fields to display on a single product page.

1. Custom measurements (accurate)
In this method, the customer has to measure and enter all the data, such as height, weight, etc.

2. Standard sizes (fast)
This is the world standard size. Small, medium, large, etc.

I have created 2 groups of custom fields and they are only visible with & # 39; Product category name & # 39;

I need to alternate between these 2 field groups when a customer selects their interested 1 or 2 measurement method.

I don't have a good knowledge of PHP, so if possible, I prefer some easy method to do it.

## sql server – Availability group notification when adding a new database

When a new database is added to the SQL Server AG configuration, a notification email is sent to us as follows.

The database of the availability group "XXXX" is changing the roles from "SECONDARY" to "SECONDARY" because the duplication session or the availability group failed due to role synchronization. This is just an informational message.

What is confusing is the phrase.

"Change roles from" SECONDARY "to" SECONDARY "…"

1. Can anyone decode the meaning of this?
2. Is it normal for such a notification to be sent when new databases are added or am I doing it wrong or any other problem?

–In & # 39; thoughts & # 39; …

## Rt representation theory: representations of the symmetric group of subgroups

Consider the finite symmetric group in $$n$$ letters $$S_n$$ Y $$chi$$ a representation in a complex vector space of finite dimensions $$V$$. Also, suppose you know the dimension of the invariant sub-vector space $$I$$ from $$V$$. To know how to decompose $$chi$$ in irreducible representations of $$S_n$$, this already gives us some information. Yes $$chi = sum_ {i = 1} ^ {p (n)} a_i T_i$$ is the decomposition of $$chi$$ in irreducible with $$T_1$$ being the trivial representation, we have $$dim V = sum a_i dim T_i$$ Y $$a_1 = dim I.$$ Now consider the set of conjugation classes of $$S_n$$, which we denote by $${C_i }$$. Choose an item $$c_i$$ in each conjugation class, and consider the group generated by it, which we denote by $$Z_i$$. Restricting $$chi$$ to each $$Z_i$$, we get a $$Z_i$$ representation in $$V$$. Suppose you also know the dimension of the invariant sub-vector space $$I_i$$ for each $$Z_i$$. With this we can get a lot of new equations, since $$dim I_i$$ it has to be equal to the trivial representation coefficient of $$Z_i$$ when we restrict $$chi$$ the.

So my question is this: is this information enough to deduce all the $$a_i$$that is, the decomposition of $$chi$$ in irreducible? In principle we are producing $$p (n) + 1$$ equations, so it should be enough if they form a basis of the vector space of dimension $$p (n)$$. I have done the calculations up $$n = 6$$, and works. In fact, I am quite convinced that this works for everyone. $$n$$, but I could not present a test … Any help would be greatly appreciated!

## Sharepoint online: how to find out if there is a current user in a group

I need to find out if a user is in a group. If so, it could show or hide properties.

I have the following code, can it be used or adapted to find out if a user is in a & # 39; group of administrators & # 39 ;?

``````let grupy = sp.web.currentUser.groups.getByName("Właściciele witryny Portal UAM").users;
console.log(grupy);
``````

One question is about the properties and the second is about the current registered user.

## javascript – How to get the email address of the users of the person or group field – using CSOM

To obtain the user's email address or username, you must use `web.ensureUser()` method and then get the email or login name as follows:

Example:

``````
function getItemFromList(){
var clientContext = new SP.ClientContext();
clientContext.executeQueryAsync(
function(){
// successfully retrieved value from list item
var assigned = item.get_item("AssignedTo");
if(assigned.length>0){
var user = clientContext.get_web().ensureUser(assigned(0).get_lookupValue());
clientContext.executeQueryAsync(
function(){
// successfully ensured user from user name
var email = user.get_email();
var displayName = user.get_title();
alert("User LoginName: " + login + "nUser Email: " + email + "nUser Display Name: " + displayName);
},function(sender,args){ // on error
}
);
}
},
function(sender,args){ // on error
}
);
}

``````

Solution for you:

Then, for your case, you can use its function in this way:

``````function FunctionToReturnEmailAddress(employeeName) {
var user = clientContext.get_web().ensureUser(employeeName);

clientContext.executeQueryAsync(
function(){
// successfully ensured user from user name
var email = user.get_email();
var displayName = user.get_title();
alert("User LoginName: " + login + "nUser Email: " + email + "nUser Display Name: " + displayName);
},function(sender,args){ // on error
}
);
}
``````

Use:

``````FunctionToReturnEmailAddress(employeeName);
``````

## 2013 – Hide field in the form of Infopath based on User Group

You can hide fields based on the SharePoint group membership in the InfoPath form. Check if the current user is a member of a group, then hide the fields if the current user is not in the group.

In the form, use GetUserProfileByName (SOAP web service: http://contoso.com/_vti_bin/UserProfileService.asmx) and GetUserCollectionFromGroup (SOAP web service: http://contoso.com/_vti_bin/UserGroup.asmx) Current user is in the specific group. If the current user is not a member of the "Hub Group" group, hide the sections to which the user does not have access.

A demonstration on how to verify if a user is a member of a SharePoint group in InfoPath:

How to: check if a user is part of a SharePoint group in a web-based InfoPath form

A blog on how to use the InfoPath data connection to create rules for hiding / disabling fields based on the current user's SharePoint group membership. Although the links are for InfoPath 2010, they should still have good information.

Information path list form: hide / disable fields based on SharePoint group membership

Or we can use the JavaScript code to achieve it. See the article below.

Show or hide form fields based on membership in a SharePoint group

## dnd 5e – How many people need to succeed in a group check with three people?

You have cited all the necessary rules for this. You put them together like this:

To do a group skill check, everyone in the group does the skill check. If at least half of the group succeeds, the entire group succeeds. Otherwise, the group fails …

Well, we need & # 39; half & # 39; of the group to succeed. What does "half" mean? In 5e we use normal language unless the book tells us to do something strange. In this case, as he quoted, the book make Tell us to do something weird instead! He says:

Whenever you divide a number in the game, round down if you end up with a fraction, even if the fraction is half or more.

So while half of 5 usually be 2.5, in this game it is 2. Similarly, when one applies these rules to the number & # 39; 3 & # 39; you can see that, because & # 39; 3 & # 39; It is an odd number, reducing it in half makes it end with a fraction. That means you round down and end up with the next whole number down, in this case & # 39; 1 & # 39 ;. Similarly, if you cut 1 by half, it would end with 0.

Keep in mind, however, that by doing this we are inventing what it means to "round down." In common language, you generally can't & # 39; round & # 39; without reference to something: & # 39; rounds to the nearest whole number & # 39; or & # 39; rounds to the nearest ten & # 39; or something like that. Used alone, the phrase is not clear: it could mean & # 39; to the nearest whole number & # 39; or & # 39; to the nearest integer & # 39; or & # 39; to the nearest non-fraction & # 39 ;, and not all of these are meanings that result in a reasonable game (although all, except & # 39; not fraction & # 39; because that is an incoherent idea in its expression usual, means 3/2 rounds to 1). Since rounding to the nearest whole number is the least terrible rule in general, when this rounding rule is used, it must be assumed that it does.

## Group theory gr: how do reflection groups relate to general point groups?

I always tried to understand how finite reflection groups from $$Bbb R ^ d$$ (of some fixed dimension $$d$$) relate to the point groups of the same space $$smash { Bbb R ^ d}$$ (finite subgroup of the orthogonal group $$smash { mathrm O ( Bbb R ^ d)}$$)

Initially, I had the impression that each group of points is a subgroup of a finite reflection group. This turned out to be incorrect, which is obvious in retrospect. Many reflection groups have symmetries in the placement of their mirrors that can be used to enlarge the group.

So let's take these expanded groups instead. From my geometric understanding, by that I mean the symmetry groups of the uniform polytopes. Then i will call you uniform dot groups. Most (or all?) Of uniform polytopes can be generated from a reflection group, and then have all the symmetries of this group, but could have more.

Question: Is each group of points a subgroup of a uniform group of points?

With regard to the answer to that question, I am open to any statement that sheds light on the location of reflection groups (or groups easily derived from them) within the family of general point groups.

## mysql – Group the results of two different tables at the same times

I have two simple tables:

inside

``````id | timestamp | temp | humi
``````

outdoor

``````id | timestamp | temp
``````

and two selections that give me time and average temperature grouped by the same hour during the last 24 hours:

``````SELECT DATE_FORMAT(timestamp, '%H:00') AS time, round(avg(temp), 1) as avg_out_temp
FROM outdoor
WHERE timestamp >= now() - INTERVAL 1 DAY
GROUP BY DATE_FORMAT(timestamp, '%Y-%m-%d %H')
ORDER BY timestamp ASC;

SELECT DATE_FORMAT(timestamp, '%H:00') AS time, round(avg(temp), 1) as avg_in_temp
FROM indoor
WHERE timestamp >= now() - INTERVAL 1 DAY
GROUP BY DATE_FORMAT(timestamp, '%Y-%m-%d %H')
ORDER BY timestamp ASC;
``````

and now what I have to do is group those two results at the same time, with respect to the possibility that there can be no records in inside or outdoor table all the time, so I need to get:

``````time | avg_out_temp | avg_in_temp
11:00 | 12.5 | 21.4
12:00 | 13.9 | null
13:00 | null | 22.4
14:00 | 14.0 | 22.5
``````


text:
### SLA_PV2EL

Orbital Elements from Position/Velocity

ACTION:
Heliocentric osculating elements obtained from instantaneous position and velocity.
CALL:
CALL sla_PV2EL (PV, DATE, PMASS, JFORMR, JFORM, EPOCH, ORBINC, ANODE, PERIH, AORQ, E, AORL, DM, JSTAT)
##### GIVEN:
 PV D(6) heliocentric $\left[\phantom{\rule{0.3em}{0ex}}x,y,z,ẋ,ẏ,ż\phantom{\rule{0.3em}{0ex}}\right]$, equatorial, J2000 (AU, AU/s; Note 1) DATE D date (TT Modified Julian Date = JD$-$2400000.5) PMASS D mass of the planet (Sun = 1; Note 2) JFORMR I requested element set (1-3; Note 3)

##### RETURNED:
 JFORM I element set actually returned (1-3; Note 4) EPOCH D epoch of elements (${t}_{0}$ or $T$, TT MJD) ORBINC D inclination ($i$, radians) ANODE D longitude of the ascending node ($\Omega$, radians) PERIH D longitude or argument of perihelion ($\varpi$ or $\omega$, radians) AORQ D mean distance or perihelion distance ($a$ or $q$, AU) E D eccentricity ($e$) AORL D mean anomaly or longitude ($M$ or $L$, radians, JFORM=1,2 only) DM D daily motion ($n$, radians, JFORM=1 only) JSTAT I status: 0 = OK $-$1 = illegal PMASS $-$2 = illegal JFORMR $-$3 = position/velocity out of allowed range

NOTES:
(1)
The PV 6-vector is with respect to the mean equator and equinox of epoch J2000. The orbital elements produced are with respect to the J2000 ecliptic and mean equinox.
(2)
The mass, PMASS, is important only for the larger planets. For most purposes (e.g. asteroids) use 0D0. Values less than zero are illegal.
(3)
Three different element-format options are supported, as follows.

JFORM=1, suitable for the major planets:

 EPOCH = epoch of elements ${t}_{0}$ (TT MJD) ORBINC = inclination $i$ (radians) ANODE = longitude of the ascending node $\Omega$ (radians) PERIH = longitude of perihelion $\varpi$ (radians) AORQ = mean distance $a$ (AU) E = eccentricity $e$$\left(0\le e<1\right)$ AORL = mean longitude $L$ (radians) DM = daily motion $n$ (radians)

JFORM=2, suitable for minor planets:

 EPOCH = epoch of elements ${t}_{0}$ (TT MJD) ORBINC = inclination $i$ (radians) ANODE = longitude of the ascending node $\Omega$ (radians) PERIH = argument of perihelion $\omega$ (radians) AORQ = mean distance $a$ (AU) E = eccentricity $e$$\left(0\le e<1\right)$ AORL = mean anomaly $M$ (radians)

JFORM=3, suitable for comets:

 EPOCH = epoch of perihelion $T$ (TT MJD) ORBINC = inclination $i$ (radians) ANODE = longitude of the ascending node $\Omega$ (radians) PERIH = argument of perihelion $\omega$ (radians) AORQ = perihelion distance $q$ (AU) E = eccentricity $e$$\left(0\le e\le 10\right)$
(4)
It may not be possible to generate elements in the form requested through JFORMR. The caller is notified of the form of elements actually returned by means of the JFORM argument:
 JFORMR JFORM meaning 1 1 OK: elements are in the requested format 1 2 never happens 1 3 orbit not elliptical 2 1 never happens 2 2 OK: elements are in the requested format 2 3 orbit not elliptical 3 1 never happens 3 2 never happens 3 3 OK: elements are in the requested format
(5)
The arguments returned for each value of JFORM (cf. Note 5: JFORM may not be the same as JFORMR) are as follows:
 JFORM 1 2 3 EPOCH ${t}_{0}$ ${t}_{0}$ $T$ ORBINC $i$ $i$ $i$ ANODE $\Omega$ $\Omega$ $\Omega$ PERIH $\varpi$ $\omega$ $\omega$ AORQ $a$ $a$ $q$ E $e$ $e$ $e$ AORL $L$ $M$ - DM $n$ - -

where:

 ${t}_{0}$ is the epoch of the elements (MJD, TT) $T$ is the epoch of perihelion (MJD, TT) $i$ is the inclination (radians) $\Omega$ is the longitude of the ascending node (radians) $\varpi$ is the longitude of perihelion (radians) $\omega$ is the argument of perihelion (radians) $a$ is the mean distance (AU) $q$ is the perihelion distance (AU) $e$ is the eccentricity $L$ is the longitude (radians, $0-2\pi$) $M$ is the mean anomaly (radians, $0-2\pi$) $n$ is the daily motion (radians) - means no value is set
(6)
At very small inclinations, the longitude of the ascending node ANODE becomes indeterminate and under some circumstances may be set arbitrarily to zero. Similarly, if the orbit is close to circular, the true anomaly becomes indeterminate and under some circumstances may be set arbitrarily to zero. In such cases, the other elements are automatically adjusted to compensate, and so the elements remain a valid description of the orbit.
(7)
The osculating epoch for the returned elements is the argument DATE.
REFERENCE:
Sterne, Theodore E., An Introduction to Celestial Mechanics, Interscience Publishers, 1960.


text:
# Question

Two players play the following game: Player A chooses one of the three spinners pictured in
Figure 2.6, and then player B chooses one of the remaining two spinners. Both players then spin their spinner, and the one that lands on the higher number is declared the winner. Assuming that each spinner is equally likely to land in any of its 3 regions, would you rather be player A or player B? Explain your answer!
FIGURE 2.6: Spinners

Sales0
Views89


text:
# Mathematical Sciences Research Institute

Home » Workshop » Schedules » Superintrinsic synthesis in fixed point properties

# Superintrinsic synthesis in fixed point properties

## Amenability, coarse embeddability and fixed point properties December 06, 2016 - December 09, 2016

December 08, 2016 (02:00 PM PST - 03:00 PM PST)
Speaker(s): Masato Mimura (Tohoku University)
Location: MSRI: Simons Auditorium
Tags/Keywords
• fixed point properties

• property (T)

• property t

• expander graph

• bounded generation

• hyperbolic groups and generalizations

• Banach space

• group cohomology

• index theory

• non-commutative geometry

Primary Mathematics Subject Classification
Secondary Mathematics Subject Classification No Secondary AMS MSC
Video

#### 14648

Abstract

The following natural question arises from Shalom's innovational work (1999, Publ.IHES) on Kazhdan's property (T). Can we establish an intrinsic' criterion to synthesize relative fixed point properties into the whole fixed point property without assuming Bounded Generation'?'' This talk is aimed to present a resolution to this question in the affirmative. Our criterion works for ones with respect to certain classes of Busemann Non-Positively Curved spaces. It, moreover, suggests a further step toward constructing super-expanders from finite simple groups of Lie type.

Supplements


text:
## Tuesday, April 01, 2008 ... /////

### Supercooling: global warming comes to Michigan

Warning: the pictures could be from Antarctica, after all, and it is not even clear whether supercooling was the only cause.
Michigan has had the coldest winter in decades. Water expands to freeze, and at Mackinaw City the water in Lake Huron below the surface ice was super-cooled.

It expanded to break through the surface ice and froze instantly into this incredible wave. Isn't it beautiful?
More 640 x 480 pictures: 01, 02, 03, 04, 05, 06, 07, 08, 09, 10, 11, 12, 13, 14, 15, 16, 17.
I've seen pictures of this wave phenomenon in Antarctica, but in Michigan? Yes, it's been quite a winter!

Hat tip: Fred Moss and Jiří Wagner

#### snail feedback (4) :

These pictures were in fact taken in antarctica and were lifted from a website and dropped into the Michigan supercooling email (so naughty!) - check it out on snopes.com where one can see ALL of the expedition's photos. Very impressive, especially the ice-wave ones. No picture of Lake Huron's ice wave...if there is one.

Lubos,
Unable to find your email address, this blog seemed the next best place to pose my question. Or should I say challenge? I firmly disagree with your position on global warming and here is why:
You are familiar with Erwin Schroedinger, no doubt, but you might also be familiar with his arguments regarding entropy. While I do not endorse everything Schroedinger says I wish to point out only one of his more compelling (if not obvious) remarks: that life is an improbable microstate which will invariably tend towards a state of maximum entropy - that state corresponding to our ultimate demise. And so given the improbable nature of life, along with the observable fact that dead bodies don't spring from the ground fully animated, we are forced to conclude that, while alive, all random motion will put one inevitably closer to that final macrostate. Global warming, pollution, eating, breathing, it all contributes towards our irreversible drift away from the initial state. The point is that, as an improbable state, the longevity of life that one experiences will depend upon their surroundings. Toxins - for instance from the air, are far more likely to do harm than good (where harm is taken as an increase in entropy). Global warming, whether caused by humans or climate variability is more likely to increase the entropy of an improbable system than to decrease it. My point is that anything but the most carefully executed action will increase the entropy within our bodies more than it increases on its own. Taking this, along with the self evident fact that human industry dramatically alters the environment without the least bit of concern for the health of those whom it affects, one must conclude that an alert public hypersensitive to even the potential consequences of imprudent mass production is a welcome shift away from pop-culture and towards something that might make a difference. So what do you have to gain from arguing against it?

Dear fonzo, what you write is not a proper interpretation of Erwin Schrödinger or a rational analysis of something but a misinterpretation of the second law of thermodynamics by a chronic pessimist.

The fact that the entropy increases doesn't mean that everything is getting worse all the time. Living objects are able to reduce their own entropy. They are very good at it. While they are doing so, they are increasing the environment's entropy even more so that the second law holds but it is a part of their strategy.

Erwin Schrödinger understood this ability of alive beings very well. Your ideas, when looked at properly, can clearly tell us nothing about climate change or its impact.

Best
Lubos


text:
# The soft heap: an approximate priority queue with optimal error rate

@article{Chazelle2000TheSH,
title={The soft heap: an approximate priority queue with optimal error rate},
author={Bernard Chazelle},
journal={J. ACM},
year={2000},
volume={47},
pages={1012-1027}
}
• B. Chazelle
• Published 1 November 2000
• Computer Science
• J. ACM
A simple variant of a priority queue, called a soft heap, is introduced. The data structure supports the usual operations: insert, delete, meld, and findmin. Its novelty is to beat the logarithmic bound on the complexity of a heap in a comparison-based model. To break this information-theoretic barrier, the entropy of the data structure is reduced by artifically raising the values of certain keys. Given any mixed sequence of n operations, a soft heap with error rate ε (for any 0 < ε ≤ 1/2…
77 Citations

## Figures from this paper

A simpler implementation and analysis of Chazelle's soft heaps
• Computer Science
SODA
• 2009
A simpler and more direct implementation of soft heaps in which each priority queue is composed of a collection of standard binary trees is described, which has the advantage that no clean-up operations similar to the ones used in Chazelle's implementation are required.
Soft Heaps Simplified
• Computer Science
SIAM J. Comput.
• 2013
A simplified implementation of soft heaps that uses less space and avoids Chazelle's dismantling operations is given and an amortized time bound of $O(\lg \frac{1}{\varepsilon})$ for each deleti...
A Selectable Sloppy Heap
A data structure called selectable sloppy heap that handles a dynamic version in which upon request a new element is inserted or an element of a prescribed quantile group is deleted from the data structure, which is the first result of this kind accommodating both insertion and deletion in constant time.
External Memory Soft Heap, and Hard Heap, a Meldable Priority Queue
• Computer Science
COCOON
• 2012
An external memory version of soft heap that is presented, which supports Insert, Findmin, Deletemin and Meld operations and guarantees that the number of corrupt elements in it is never more than eN, where N is the total number of items inserted in it, and e is a parameter of it called the error-rate.
SprayLists : Provably Correct Approximate Priority Queues in a Shared Memory Setting
• Jerry Li
• Computer Science, Mathematics
• 2013
An important data structure well understood in sequential settings is the priority queue, which supports the following three operations: insert(x), which inserts an item with priority x, delete(x),
Soft Sequence Heaps
The main contribution of this paper is an alternative soft heap implementation based on merging sorted sequences, with time bounds matching those of Chazelle's soft heaps, which is based on ternary trees instead of binary trees and matches the time bounds of Kaplan et al.
Selectable Heaps and Their Application to Lazy Search Trees
• Computer Science
• 2021
The presented data structure uses soft heaps of Chazelle, biased search trees, and efficient priority queues in a non-trivial way, approaching the theoretically-best data structure for ordered data.
Efficient Algorithms and Data Structures for Massive Data Sets
• Alka
• Computer Science
ArXiv
• 2010
This thesis proposes two variants of the W-Stream model, and design algorithms for the maximal independent set, vertex-colouring, and planar graph single source shortest paths problems on those models.
Selectable Heaps and Optimal Lazy Search Trees
• Computer Science
SODA
• 2022
The presented data structure makes fundamental use of soft heaps, biased search trees, and efficient priority queues, approaching the theoretically-best data structure for ordered data.
2 Dynamic Ordered Sets with Approximate Queries , Approximate Heaps & Soft Heaps 1
• Computer Science
• 2019
This work considers word RAM data structures for maintaining ordered sets of integers whose select and rank operations are allowed to return approximate results, and proves the optimality of all the data structures presented, either through matching cell-probe lower bounds, or through equivalences to well studied static problems.

## References

SHOWING 1-10 OF 12 REFERENCES
Fibonacci Heaps and Their Uses in Improved Network Optimization Algorithms
• Computer Science, Mathematics
FOCS
• 1984
The structure, Fibonacci heaps (abbreviated F-heaps), extends the binomial queues proposed by Vuillemin and studied further by Brown to obtain improved running times for several network optimization algorithms.
Fibonacci heaps and their uses in improved network optimization algorithms
• Physics
JACM
• 1987
Using F-heaps, a new data structure for implementing heaps that extends the binomial queues proposed by Vuillemin and studied further by Brown, the improved bound for minimum spanning trees is the most striking.
A minimum spanning tree algorithm with inverse-Ackermann type complexity
A deterministic algorithm for computing a minimum spanning tree of a connected graph that uses pointers, not arrays, and it makes no numeric assumptions on the edge costs.
A data structure for manipulating priority queues
A data structure is described which can be used for representing a collection of priority queues. The primitive operations are insertion, deletion, union, update, and search for an item of earliest
Time Bounds for Selection
• Mathematics
J. Comput. Syst. Sci.
• 1973
A minimum spanning tree algorithm with inverseAckermann type complexity
• J . ACM
• 2000
A minimum spanning tree algorithm with inverseA kermann type omplexity , to appear
• Prelim . version in A faster deterministi algorithm for minimum spanning trees , Pro . 38 th Ann . IEEE Symp . Found . Comp . S i .
• 1997
Sorting Jordan sequen es inlinear time using levellinked sear h trees
• Inform . and Control
• 1986
Time bounds for
• 1973


text:
# Degree of Time Dilation At a Distance From the Sun where acceleration = g?

At higher altitudes above a body, clocks tick more slowly, and gravitational field is weaker. But what is the relationship? It is tempting for a GR newbie such as myself to think that anywhere that the gravity is equal to that of the earth's surface that time-dilation would be the same, i.e. dilation as a simple function of local gravitational acceleration. I have been assured that this is not the case. I wonder if someone can calculate the following situation, which strikes me as the simplest 2nd case to compare with earth's surface: At the surface of the Sun, gravity is roughly 28 times that at the Earth's surface. If we move out to a suitable distance, we can find a place where the gravitational acceleration is the same as the surface of the Earth - 1g - and we can hold a clock there with a rocket. What is the time dilation there with regard to a "Far away" observer? I understand to the dilation on the Earth's surface to be 0.0219 seconds per year compared with the distant observer.

-
I gave you a +1 because somebody gave you a -1 without a comment. To the downvoter, you should really post. Anyway, time dilation has to do with your speed. At that distance from the sun, you will be able to calculate an orbital speed. Try doing that and seeing the results :) – markovchain Feb 4 '13 at 5:09
@markovchain, time dilation in special relativity is to do with speed. In general relativity, gravitational fields can cause time dilation with respect to an observer even when stationary with respect to the same observer. – Mew Feb 4 '13 at 7:17
Dudes, this is a general relativity question. Speed is to be neglected here. – Jonathan Dunn Feb 4 '13 at 14:05

For a Schwarzschild observer the gravitational time dilation means the local time at a distance $r$ from a mass $M$, appears to be running slow by a factor of:

$$\sqrt {1 - \frac{2GM}{r c^2}}$$

You get this straight from the Schwarzschild metric:

$$ds^2 = -\left(1-\frac{2GM}{r c^2}\right)dt^2 + \left(1-\frac{2GM}{r c^2}\right)^{-1}dr^2 + r^2 d\Omega^2$$

because hovering above the Sun, both $dr$ and $d\Omega$ are zero.

Anyhow, I reckon the acceleration due to the Sun's gravity is 9.81m/s$^2$ at a distance of about $3.68 \times 10^9$m (using the Newtonian expression for $a$), and at this distance I work out the time dilation to be about 12.6 seconds per year. So the time dilation is not simply proportional to the gravitational acceleration.

You can get an approximate, but very good, relationship between the acceleration and the time dilation by using the Newtonian expression for the acceleration to get $r$ and substituting in the expression for the time dilation. Doing this gives:

$$\sqrt{1 - \frac{2\sqrt{aGM}}{c^2}}$$

which I don't think is terribly illuminating!

-
If you take the limit of your last expression for small $a$ and $GM$, and take the difference between the values of the expression for Earth and the sun you get that $\delta\sqrt{\cdots}\approx\sqrt{\frac{M_{sun}}{M_{Earth}}}\sqrt{\text{Earth}}$ (I hope the notation is obvious): the difference is proportional to the square root of the mass ratio. So if I made no mistakes the time dilation at the sun should be 577 times bigger than the Earth's, which agrees with your numbers. – Michael Brown Feb 4 '13 at 14:05


text:
# Daltons Law Formula

Dalton’s Law of partial pressure states that “the total pressure exerted by the mixture of gases is the sum of all the partial pressure of the individual gases.” Partial pressure is the pressure exerted by a gas present in a mixture of gases.

In other words, Dalton’s law of partial pressures is applied in determining the individual pressure of every single gas in a gaseous mixture.

Dalton’s Law can be expressed mathematically as

Where,

Ptotal is the total pressure of a gaseous mixture and

P1, P2, P3 are the partial pressures of the individual gases.

Example 1

Determine the partial pressure of H2 at 20oC when the vapour pressure of water is 17.5torr.  If the total pressure of the gas is 750 torr.

Solution

The Given values are

Ptotal = 750 torr

PH20 = 17.5torr

PH2 =?

By applying Dalton’s Formula, we get

Ptotal =PH20 + PH2

750 torr = 17.5torr + PH2

PH2 = 732 torr

Example 2

Three gases H2, N2 and Ar, are mixed in a container of 500L. The pressure of Ar is 255 torr; N2 is 228 torr and H2 is 752 torr. Calculate the total pressure in the container.

Solution

We know that the total pressure is the sum of the partial pressure of each gas.


text:
# Why can't Mathematica solve this definite integral?

I want to solve the integral

$$\int_{p_0}^{p_1}\left(T_0+\Gamma_p(p_0-p)\right)\frac{1}{p}dp$$

Mathematica can do the indefinite integral immediately:

>>> Integrate[(T + Γ (p0 - p))*(1/p), p]
-p Γ + (T + p0 Γ) Log[p]

But addind bounds suddenly makes it choke, i.e. the following never returns:

>>> Integrate[(T + Γ (p0 - p))*(1/p), {p, p0, p1}]

even though I can do this just fine:

FullSimplify[Limit[-Γ p + (Γ P + T) Log[p], p -> p1] - Limit[-Γ p + (Γ P + T) Log[p], p -> p0]]

What is the issue?

• Is the subscript $p$ on $\Gamma$ in the first equation a typo? Is that not the same $p$ as the integration variable? Sep 23 at 12:26

Likely this is due to the fact that antiderivative are troublesome in computer algebra systems. Do this:

Integrate[(T + \[CapitalGamma] (p0 - p))*(1/p), {p, p0, p1},   Assumptions -> {p1 > p0 > 0}]

Assuming, of course, that p1 > p0 > 0 is actually true.

• +1 for linking back to that Wolfram blog post. Sep 23 at 15:02

Mathematica likely has problems with four parameters which are assumed to be complex numbers and an antiderivative with branches. The GenerateConditions -> False/True option does the job.

Integrate[(T + \[CapitalGamma] (p0 - p))*(1/p), {p, p0, p1}, GenerateConditions -> False]

p0 - p1) \[CapitalGamma] - (T + p0 \[CapitalGamma]) Log[ p0] + (T + p0 \[CapitalGamma]) Log[p1]

Integrate[(T +\[CapitalGamma] (p0 - p))*(1/p), {p, p0, p1},
Assumptions -> {p0, p1, \[CapitalGamma],T} \[Element] Reals,GenerateConditions -> True]

ConditionalExpression[(p0 - p1) \[CapitalGamma] + (T + p0 \[CapitalGamma]) Log[p1/p0], p0 > 0 && p0 != p1 && p1 > 0]


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# Bold symbols in equations?

How to bold symbols in equations? I used the code ‘\boldsymbol’ and ‘\bm’, they all don’t work.

I use \textbf{x}.

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It works, but not so good. The export result is text, not an equation.

I tried \mathbf{\gamma}, it is ok.

Apparently this is an ongoing issue in MathJax. It seems Obsidian needs to set a flag for boldsymbol.

This didn’t really work for me. \pmb{\gamma} gave me proper bold greek symbols. It’s definitely confusing but I’m having these issues in other programs using MathJax as well (Anki).

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