[petsc-users] Loading only upper + MatSetOption(A,MAT_SYMMETRIC,PETSC_TRUE);

[Klaus Burkart via petsc-users]

Hello,

I want to solve many symmetric linear systems one after another in parallel 
using boomerAMG + KSPCG  and need to make the matrix transfer more efficient. 
Matrices are symmetric in structure and values. boomerAMG + KSPCG work fine.

So far I have been loading the entire matrices but I read in a paper, that it's 
sufficient to load the upper part only and tell petsc that the matrix is 
symmetric using MatSetOption(A,MAT_SYMMETRIC,PETSC_TRUE); Unfortunately all 
computations fail if I load only the upper values and use 
MatSetOption(A,MAT_SYMMETRIC,PETSC_TRUE);
The idea is:
    if (matrix_.symmetric())
    {
        MatSetOption(A,MAT_SYMMETRIC,PETSC_TRUE);
       //load only upper part of the matrix MatSetValues(...)

   }else //asymmetric matrix
           {               //load the entire matrix MatSetValues(...)
           }

Is it possible at all? 

Klaus