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A simple matrix with interesting inverse 31 Mar 2021
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0-tri101-inverse.md

A simple matrix with interesting inverse

Keywords: sparse linear solver, python, scipy, testcase, matrix, GMRES, poisson, plot

2apr-tri101-inv

A simple testcase for GMRES

Wikipedia GMRES says

fast convergence occurs when the eigenvalues of A are clustered away from the origin

But what if they're not ?

(There's a great divide between solvers for Ax = b for A symmetric, or not, or non-normal; see how-does-gmres-method-iteration-behave-for-this-non-diagonalizable-matrix .)

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