[petsc-users] Reading values from a matrix into a different format

[Tim Steinhoff]

Hi all

assume that a sparse matrix is constructed via

MPI_Comm comm;
Mat A;
PetscInt n = 10000; /* dimension of matrix */
comm = PETSC_COMM_SELF;
MatCreate(comm,&A);
MatSetSizes(Amat,n,n,n,n);
MatSetBlockSize(A,6);
MatSetType(A,MATAIJ);

followd by some suitable preallocation and setting of values.

What can be done to efficiently read the values from the matrix A and
store them in a format like the coordinate format COO?

Regards
Tim