[petsc-users] [slepc] nan output for eigenvectors

I sometimes get Nan output values in computed eigenvectors for the generalized symmetric eigenvalue problem produced by slepc. Is this a known issue, and is it related to the conditioning of the matrix pair (A,B)? Is there some way to compute a "condition number" of the matrix pair ahead of time

Re: [petsc-users] Using matrix-free with KSP

> On Sep 6, 2022, at 11:00 PM, Tu, Jiannan wrote: > > I am using TS IMEX to solve a large DAE system. The DAE is obtained by > applying finite FV method to 3-D multi-specie ion/neutral fluids equations > with magnetic induction equation. The Jacobian for stiff part is formed by > using

Re: [petsc-users] Using matrix-free with KSP

You can refer to the example src/ts/tutorials/advection-diffusion-reaction/ex5adj_mf.c which uses a matrix-free approach for a 2D multi-component reaction-diffusion PDE. In particular, you only need to look at MyIMatMult() and ignore the transposed version which is intended for adjoint

Re: [petsc-users] Using matrix-free with KSP

I am using TS IMEX to solve a large DAE system. The DAE is obtained by applying finite FV method to 3-D multi-specie ion/neutral fluids equations with magnetic induction equation. The Jacobian for stiff part is formed by using MatSetValuesStencil(). The Jacobian matrix is very sparse, no more

Re: [petsc-users] PETSc with gcc/gfortran

Thank you, Satish and Barry! I will try to re-build PETSc with gcc compiler. Best regards, -Han > On Sep 6, 2022, at 10:23 AM, Satish Balay wrote: > > Did you rebuild PETSc with gnu compilers? > > You can have both builds of PETSc (one with Intel compilers, the other with > GNU compilers) by

Re: [petsc-users] PETSc with gcc/gfortran

Did you rebuild PETSc with gnu compilers? You can have both builds of PETSc (one with Intel compilers, the other with GNU compilers) by building each with a different PETSC_ARCH value ./configure PETSC_ARCH=arch-intel --with-cc=icc ... ..configure PETSC_ARCH=arch-gnu --with-cc=gcc ... And

Re: [petsc-users] PETSc with gcc/gfortran

This happens when the module files were created with one Fortran compiler, say ifort`, but it is attempting to read them with a different Fortran compiler, say gfortran. (You can never mix to different Fortran compilers in the same executable/library/module system. You need to use a

[petsc-users] PETSc with gcc/gfortran

I used to compile my Fortran 90 code using intel compilers (i.e. intel and impi). However, when I tried to compile using gcc, it gave the following error. use petscksp 1 Fatal Error: File 'petscksp.mod' opened at (1) is not a GNU Fortran module file It would be appreciated if you could