2: static char help[] = "Passes a sparse matrix to Matlab.\n\n";

 4:  #include petscmat.h

  8: int main(int argc,char **args)
  9: {
 11:   PetscInt       m = 4,n = 5,i,j,I,J;
 12:   PetscScalar    one = 1.0,v;
 13:   Vec            x;
 14:   Mat            A;

 16:   PetscInitialize(&argc,&args,(char *)0,help);
 17:   PetscOptionsGetInt(PETSC_NULL,"-m",&m,PETSC_NULL);
 18:   PetscOptionsGetInt(PETSC_NULL,"-n",&n,PETSC_NULL);

 20:   MatCreate(PETSC_COMM_WORLD,&A);
 21:   MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,m*n,m*n);
 22:   MatSetFromOptions(A);

 24:   for (i=0; i<m; i++) {
 25:     for (j=0; j<n; j++) {
 26:       v = -1.0;  I = j + n*i;
 27:       if (i>0)   {J = I - n; MatSetValues(A,1,&I,1,&J,&v,INSERT_VALUES);}
 28:       if (i<m-1) {J = I + n; MatSetValues(A,1,&I,1,&J,&v,INSERT_VALUES);}
 29:       if (j>0)   {J = I - 1; MatSetValues(A,1,&I,1,&J,&v,INSERT_VALUES);}
 30:       if (j<n-1) {J = I + 1; MatSetValues(A,1,&I,1,&J,&v,INSERT_VALUES);}
 31:       v = 4.0; MatSetValues(A,1,&I,1,&I,&v,INSERT_VALUES);
 32:     }
 33:   }
 34:   MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
 35:   MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);
 36: #if defined(PETSC_USE_SOCKET_VIEWER)
 37:   MatView(A,PETSC_VIEWER_SOCKET_WORLD);
 38: #endif
 39:   VecCreateSeq(PETSC_COMM_SELF,m,&x);
 40:   VecSet(x,one);
 41: #if defined(PETSC_USE_SOCKET_VIEWER)
 42:   VecView(x,PETSC_VIEWER_SOCKET_WORLD);
 43: #endif
 44: 
 45:   PetscSleep(30);

 47:   VecDestroy(x);
 48:   MatDestroy(A);
 49:   PetscFinalize();
 50:   return 0;
 51: }
 52: