John Francis developed the QR algorithm, an algorithm for finding the eigenvalues and eigenvectors of a matrix. Some experts regard the QR algorithm as one of the 10 most important numerical algorithms of the 20th century. He developed the algorithm in 1959 but then left the numerical analysis community three years later. The NA Digest article doesn’t say whether Francis became a recluse or simply moved on to a job outside mathematics. No one in numerical analysis knew anything about him until a couple folks tracked him down recently. He is doing well. He remembers his earlier work clearly but was unaware of the impact it had had.
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