About unpreconditioned residuals in Left Preconditioned GMRES

Dave May dave.mayhem23 at gmail.com
Sat Feb 2 07:29:33 CST 2008

    You can use the function

PetscErrorCode PETSCKSP_DLLEXPORT KSPSetConvergenceTest(KSP

to define your own convergence test.


2008/2/2 jiaxun hou <jiaxun_hou at yahoo.com.cn>:

> Hi everyone,
> I want to use the Left Preconditioned GMRES to solve a linear system, and
> the stopping criterion  must  be  based on the  actual residuals (b-Ax). But
> the  GMRES codes of PETSc seems to use the preconditioned residuals
> (B^-1(b-Ax)) only. In addition,  when I set
> KSPSetNormType(ksp,KSP_NORM_UNPRECONDITIONED), I receive the error message:
> "Currently can use GMRES with only preconditioned residual (right
> preconditioning not coded)". So, is there any way to set stopping criterion
> based on the actual residuals?
> Best regards,
> Jiaxun
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