Actual source code: ex8.c


  2: static char help[] = "Tests automatic allocation of matrix storage space.\n\n";

  4: #include <petscmat.h>

  6: int main(int argc,char **args)
  7: {
  8:   Mat            C;
  9:   PetscInt       i,j,m = 3,n = 3,Ii,J;
 10:   PetscScalar    v;
 11:   MatInfo        info;

 13:   PetscInitialize(&argc,&args,(char*)0,help);
 14:   PetscOptionsGetInt(NULL,NULL,"-m",&m,NULL);
 15:   PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL);

 17:   /* create the matrix for the five point stencil, YET AGAIN */
 18:   MatCreate(PETSC_COMM_SELF,&C);
 19:   MatSetSizes(C,PETSC_DECIDE,PETSC_DECIDE,m*n,m*n);
 20:   MatSetFromOptions(C);
 21:   MatSetUp(C);
 22:   for (i=0; i<m; i++) {
 23:     for (j=0; j<n; j++) {
 24:       v = -1.0;  Ii = j + n*i;
 25:       if (i>0)   {J=Ii-n; MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES);}
 26:       if (i<m-1) {J=Ii+n; MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES);}
 27:       if (j>0)   {J=Ii-1; MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES);}
 28:       if (j<n-1) {J=Ii+1; MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES);}
 29:       v = 4.0; MatSetValues(C,1,&Ii,1,&Ii,&v,INSERT_VALUES);
 30:     }
 31:   }
 32:   MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);
 33:   MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);
 34:   MatView(C,PETSC_VIEWER_STDOUT_SELF);

 36:   MatGetInfo(C,MAT_LOCAL,&info);
 37:   PetscPrintf(PETSC_COMM_SELF,"matrix nonzeros = %" PetscInt_FMT ", allocated nonzeros = %" PetscInt_FMT "\n",(PetscInt)info.nz_used,(PetscInt)info.nz_allocated);

 39:   MatDestroy(&C);
 40:   PetscFinalize();
 41:   return 0;
 42: }

 44: /*TEST

 46:    test:

 48: TEST*/