[Trilinos-Users] Question about GCRODR in Belos

Wen Yan wenyan4work at gmail.com
Thu Aug 9 12:42:46 EDT 2018

Dear Trilinos users,

I am trying to use GCRODR to solve a sequence of linear systems Ax_i=b_i, where the operator A does not change but the right side b_i slightly changes. The setup of GCRODR works, and the reported number of iterations after the first linear system is reduced compared to cases using PseudoBlockGMRES. However, I found that inside GCRODR->solve() and before the iterations, the operator A is applied to one multi vector with column number equal to the number of recycled vectors. Therefore there is no saving in computational time. I was using default parameters for GCRODR.

I was wondering if this is the expected behavior of GCRODR, or if there is a switch controlling it. I didn’t find that on the document webpage. 

Thank you!
Wen Yan

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