#include <petsc.h>

#undef __FUNCT__
#define __FUNCT__ "main"
int main(int argc,char **args)
{
  Mat            A,R,ARt,C;
  PetscInt       ai[5] = {0,2,4,6,8};
  PetscInt       aj[8] = {0,3,1,2,1,2,0,3};
  PetscReal      av[8] = {1,2,3,4,5,6,7,8};
  PetscInt       ri[3] = {0,1,2};
  PetscInt       rj[2] = {1,2};
  PetscReal      rv[2] = {1,1};
  PetscErrorCode ierr;

  PetscInitialize(&argc,&args,(char *)0,(char *)0);

  ierr = MatCreateSeqAIJWithArrays(PETSC_COMM_WORLD,4,4,ai,aj,av,&A);CHKERRQ(ierr);
  ierr = MatCreateSeqAIJWithArrays(PETSC_COMM_WORLD,2,4,ri,rj,rv,&R);CHKERRQ(ierr);

  //this is ok:
  //ierr = MatMatTransposeMult(A,R,MAT_INITIAL_MATRIX,1.0,&ARt);CHKERRQ(ierr);
  //ierr = MatMatMult(R,A,MAT_INITIAL_MATRIX,1.0,&C);CHKERRQ(ierr);
  //ierr = MatView(C, PETSC_VIEWER_STDOUT_SELF);CHKERRQ(ierr);

  //this is not:
  ierr = MatRARt(A,R,MAT_INITIAL_MATRIX,1.0,&C);CHKERRQ(ierr);

  ierr = PetscFinalize();
  return 0;
}