# Tagged Questions

The nonlinear-equations tag has no wiki summary.

1answer
23 views

### How do I extrapolate data from a NON-LINEAR (logarithmic) standard curve in Excel?

I have made a standard curve. The X-axis is logarithmic. The y-axis is linear. I have added a logarithmic trendline (y = -1.546ln(x) + 39.254; R² = 0.9906). How can I re-arrange the equation to ...
2answers
68 views

### Problems where SPD linear system arises

I know some of the places where SPD linar systems arises such as elliptic PDEs and normal equations. Can I have a more comprehensive list of scientific applications which require solving SPD linear ...
4answers
152 views

### How to find more than one root of a polynomial?

This program finds the first root of the function f, defined in the code. There are 5 roots of this function. (x=1,2,3,4,5) I wish to find all of the roots in this program and print them to the ...
2answers
116 views

### C++ alternatives for simulating dynamic systems

I'm looking for alternatives to Matlab/Simulink and Dymola for simulating a non-linear dynamic system. I know it's possible to implement the time-domain behavior without a lot of code and a good ...
1answer
75 views

### Non-linear root finding when the Jacobian is almost singular

I'm trying to solve a system non linear-equations: $$\frac{\partial K(\mathbf{\lambda})}{\partial \lambda_i} - c_i = 0$$ for $i = 1, \dots, 15$, using Newton's method:  \lambda^{k + 1} = \lambda^k ...
1answer
73 views

### Stability of numerical schemes for non-linear equations with a Jacobian with negative eigenvalues

Let us assume I have an A-stable numerical scheme. I believe that given any linear equation $y' = Ay$, it means that the numerical scheme applied to this equation is stable (and therefore convergent ...
4answers
164 views

### parameters estimation

I have to estimate a parameter (K), but I don't know how I can do it. I think by a regression model (minimum least square?), but I'm not sure. The system is: ...
2answers
84 views

### Solving a nonlinear algebraic system that includes a linear term

I am trying to solve a particular system of non linear equations written as $F(x) = 0$ in an efficient way. More specifically, $$F(x) = (I - \gamma A)x - g(x) + C$$ where $\gamma$ is a ...
0answers
134 views

### solving nonlinear differential equations by finite differences+matlab code [closed]

Here is the equation that I don't know how to solve by finite differences. I will appreciate when someone can help me.  \frac{\partial{^2T}}{\partial{x^2}} = 0.01 \cdot (T-20)^4 \\ T(0) = 200 \\ ...
1answer
110 views

### Nonlinear dynamics: algorithm suggest

I've just started a thesis on nonlinear dynamics which entails numerical analysis of the Duffing oscillator (DO). It's basically just a second order ODE, or equivalently a set of ODEs. Say, after ...
1answer
177 views

### Nonlinear wave equation - Finite element or finite difference

I would like to know the which is more advantageous when it comes to solving nonlinear hyperbolic equations, Finite Element or Finite difference methods? Which method will be better in capturing ...
2answers
112 views

### How to do upwinding in finite volume schemes for nonlinear equations?

In finite difference theory, you learn, that you have to use upwinding for equations with high convection, like Burgers' equation. What does the finite volume equivalent look like? What if the ...
0answers
167 views

### Numerical method for nonlinear system of algebraic equations of special type

I have a nonlinear system of algebraic equations of special kind:  \begin{array}{rcl} x_{i}+y_{i}+z_{0,1}+c_{i,1}z_{1,1} & = & d_{i,1}, \\ x_{i}^2 + y_{i}^2 + z_{0,2} + c_{i,1} ...
1answer
452 views

### Newton-Raphson method for nonlinear partial differential equations

For the numerical solution of Reynolds equations (a non-linear partial differential equation), the Newton-Raphson method is generally proposed. After getting algebraic equations from a finite ...
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