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1
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0answers
43 views

Petsc solver problem

I have to resolve the linear equation Ax = B in which A is not symmetrical, either definite positive. I used the solver GMRES of Petsc. It seems to work well but with the same configuration (initial ...
2
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0answers
179 views

GMRES implementations

I am looking for simple GMRES implementations. Unfortunately, I have a few requirements: should be C or Fortran, Fortran preferred needs a license that permits inclusion in an MIT/BSD licensed ...
12
votes
3answers
664 views

Problems where Conjugate gradient works much better than GMRES

I am interested in cases where Conjugate gradient works much better than GMRES method. In general, CG is preferable choice in many cases of SPD (symmetric-positive-definite) because it requires less ...
3
votes
2answers
86 views

Parameter selection difficulty in GMRES

we are using a first order implicit finite volume code for simulation of incompressible flows. At its core, the code utilizes a (non-preconditioned) GMRES method for solving linear systems given in ...
1
vote
1answer
256 views

GMRES Matlab 'tol' parameter

I need to use GMRES solver in MATLAB, and I need to play around with the codes parameters and I had a very simple question about its usage. The documentation of the solver here mentions a parameter ...
6
votes
4answers
936 views

Best choice of solver for a large sparse symmetric (but not positive definite) system

I am presently working on solving very large symmetric (but not positive definite) systems, generated by some certain algorithms. These matrices have a nice block sparsity which can be used for ...
2
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0answers
222 views

Cusp Library performance worse than PETSC (GMRES 200 iterations) Why?

I wanted to compare the speeds of the GMRES implementations in the CUSP and the PETSc libraries. The matrix (A) used for testing was a 3d Laplacian matrix obtained by using the 7 point stencil on a ...