static char help[] = "Testing PtAP for SeqMAIJ matrix, P, with SeqAIJ matrix, A.\n\n";

#include "petscmat.h"

#undef __FUNCT__
#define __FUNCT__ "main"
int main(int argc,char **argv) {
  Mat            pA,P,aijP;
  PetscScalar    pa[]={1.,-1.,0.,0.,1.,-1.,0.,0.,1.};
  PetscInt       pij[]={0,1,2};
  PetscInt       aij[3][3]={{0,1,2},{3,4,5},{6,7,8}};
  Mat            A,mC,C;
  PetscScalar    one=1.;
  PetscErrorCode ierr;

  PetscInitialize(&argc,&argv,(char *)0,help);

  /* Create MAIJ matrix, P */
  ierr = MatCreate(PETSC_COMM_SELF,&pA);CHKERRQ(ierr);
  ierr = MatSetSizes(pA,3,3,3,3);CHKERRQ(ierr);
  ierr = MatSetType(pA,MATSEQAIJ);CHKERRQ(ierr);
  ierr = MatSetOption(pA,MAT_IGNORE_ZERO_ENTRIES);CHKERRQ(ierr);
  ierr = MatSetValues(pA,3,pij,3,pij,pa,ADD_VALUES);CHKERRQ(ierr);
  ierr = MatAssemblyBegin(pA,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
  ierr = MatAssemblyEnd(pA,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
  ierr = MatCreateMAIJ(pA,3,&P);CHKERRQ(ierr);
  ierr = MatDestroy(pA);

  /* Create AIJ equivalent matrix, aijP, for comparison testing */
  ierr = MatConvert(P,MATSEQAIJ,MAT_INITIAL_MATRIX,&aijP);

  /* Create AIJ matrix, A */
  ierr = MatCreate(PETSC_COMM_SELF,&A);CHKERRQ(ierr);
  ierr = MatSetSizes(A,9,9,9,9);CHKERRQ(ierr);
  ierr = MatSetType(A,MATSEQAIJ);CHKERRQ(ierr);
  ierr = MatSetOption(A,MAT_IGNORE_ZERO_ENTRIES);CHKERRQ(ierr);
  ierr = MatSetValues(A,3,aij[0],3,aij[0],pa,ADD_VALUES);CHKERRQ(ierr);
  ierr = MatSetValues(A,3,aij[1],3,aij[1],pa,ADD_VALUES);CHKERRQ(ierr);
  ierr = MatSetValues(A,3,aij[2],3,aij[2],pa,ADD_VALUES);CHKERRQ(ierr);
  {int i;
   for (i=0;i<9;i++) {
    ierr = MatSetValue(A,i,i,one,ADD_VALUES);CHKERRQ(ierr);
   }
  }
  ierr = MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
  ierr = MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
  
  /* Perform SeqAIJ_SeqMAIJ PtAP */
  ierr = MatPtAP(A,P,MAT_INITIAL_MATRIX,1.,&mC);CHKERRQ(ierr);
  ierr = MatView(mC,PETSC_VIEWER_STDOUT_SELF);CHKERRQ(ierr);

  /* Perform SeqAIJ_SeqAIJ PtAP for comparison testing */
  ierr = MatPtAP(A,aijP,MAT_INITIAL_MATRIX,1.,&C);CHKERRQ(ierr);
  ierr = MatView(C,PETSC_VIEWER_STDOUT_SELF);CHKERRQ(ierr);

  /* Perform diff of two matrices */
  ierr = MatAXPY(C,-1.0,mC,DIFFERENT_NONZERO_PATTERN);CHKERRQ(ierr); 
  /* Note: We should be able to use SAME_NONZERO_PATTERN on the line above, */
  /*       but don't because this flag doesn't assist testing. */
  ierr = MatView(C,PETSC_VIEWER_STDOUT_SELF);CHKERRQ(ierr);

  /* Cleanup */
  ierr = MatDestroy(P);
  ierr = MatDestroy(aijP);
  ierr = MatDestroy(A);
  ierr = MatDestroy(C);
  ierr = MatDestroy(mC);
  PetscFinalize();
  return(0);
}