[petsc-users] PetscFinalize in the middle of the C program

[Barry Smith]

> On May 6, 2015, at 4:16 AM, siddhesh godbole <siddhesh4godbole at gmail.com> wrote:
> 
> Hello,
> 
> I want to close the PETSc environment in the middle of my C program but want to retain the matrices generated in PETSc and access them using C program. How can i /(Can I) do this? 
> 
> To be precise, i am solving eigenvalue system using SLEPc and i am using the results to decouple the system matrices. Now i want to run the Newmark integration code on those matrices. I am getting very slow performance by PETSc routines such as
> MatGetColumnVector()
> VecGetArray()
> MatAXPY()
> VecAXPBYPCZ()
>  So i just want to close the PETSc environment and retain these matrices and solve using available Newmark code in C using mpi.  Need your inputs.
> 
   You cannot call PetscFinalize() and then continue to use PETSc matrices; but you can avoid using routines that are slow for you. Now MatGetColumnVector() and MatAXPY() can be slow depending on the matrices nonzero structure but VecGetArray() and VecAXPBYPCZ() will never be slow. Perhaps you need to look at the timings more carefully to see where the time is being spent. For example run with -log_summary and email the results to us so we can determine what is causing your slow performance.

  Barry

   
> Thank you very much
> 
> Siddhesh M Godbole
> 
> 5th year Dual Degree,
> Civil Eng & Applied Mech.
> IIT Madras