Hi Mark, Thanks for your reply!
Maybe I have a misunderstanding of the documentation of KSPComputeRitz (https://petsc.org/main/docs/manualpages/KSP/KSPComputeRitz/). It says "-this is currently not implemented when PETSc is built with complex numbers". But if it works, I will give it a try. Thanks, Feng <https://petsc.org/main/docs/manualpages/KSP/KSPComputeRitz/> ________________________________ From: Mark Adams <[email protected]> Sent: 14 July 2022 12:23 To: feng wang <[email protected]> Cc: [email protected] <[email protected]> Subject: Re: [petsc-users] KSPComputeRitz, GMRES, matrix with complex number Why do you say it only works with Real? You need to configure PETSc to use complex numbers and it should work. This is an advanced method and it does not have any tests, which basically says it is very experimental. Don't expect it to be very robust. Mark On Thu, Jul 14, 2022 at 7:19 AM feng wang <[email protected]<mailto:[email protected]>> wrote: Dear All, I am using GMRES with complex numbers and would like to compute the Ritz values. I am looking at KSPComputeRitz<https://petsc.org/main/docs/manualpages/KSP/KSPComputeRitz/> and it seems to me that it only works with Petsc compiled with real numbers. Is there an easy alternative way to compute Ritz values for matrices with complex numbers? Thanks, Feng
