Actual source code: ex9.c

  2: static char help[] = "Tests MPI parallel matrix creation.\n\n";

  4: #include <petscmat.h>

  8: int main(int argc,char **args)
  9: {
 10:   Mat            C;
 11:   MatInfo        info;
 12:   PetscMPIInt    rank,size;
 13:   PetscInt       i,j,m = 3,n = 2,low,high,iglobal;
 14:   PetscInt       Ii,J,ldim;
 16:   PetscBool      flg;
 17:   PetscScalar    v,one = 1.0;
 18:   Vec            u,b;

 20:   PetscInitialize(&argc,&args,(char *)0,help);
 21:   MPI_Comm_rank(PETSC_COMM_WORLD,&rank);
 22:   MPI_Comm_size(PETSC_COMM_WORLD,&size);
 23:   n = 2*size;

 25:   MatCreate(PETSC_COMM_WORLD,&C);
 26:   MatSetSizes(C,PETSC_DECIDE,PETSC_DECIDE,m*n,m*n);
 27:   MatSetFromOptions(C);

 29:   /* Create the matrix for the five point stencil, YET AGAIN */
 30:   for (i=0; i<m; i++) {
 31:     for (j=2*rank; j<2*rank+2; j++) {
 32:       v = -1.0;  Ii = j + n*i;
 33:       if (i>0)   {J = Ii - n; MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES);}
 34:       if (i<m-1) {J = Ii + n; MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES);}
 35:       if (j>0)   {J = Ii - 1; MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES);}
 36:       if (j<n-1) {J = Ii + 1; MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES);}
 37:       v = 4.0; MatSetValues(C,1,&Ii,1,&Ii,&v,INSERT_VALUES);
 38:     }
 39:   }

 41:   /* Add extra elements (to illustrate variants of MatGetInfo) */
 42:   Ii = n; J = n-2; v = 100.0;
 43:   MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES);
 44:   Ii = n-2; J = n; v = 100.0;
 45:   MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES);

 47:   MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);
 48:   MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);

 50:   /* Form vectors */
 51:   VecCreate(PETSC_COMM_WORLD,&u);
 52:   VecSetSizes(u,PETSC_DECIDE,m*n);
 53:   VecSetFromOptions(u);
 54:   VecDuplicate(u,&b);
 55:   VecGetLocalSize(u,&ldim);
 56:   VecGetOwnershipRange(u,&low,&high);
 57:   for (i=0; i<ldim; i++) {
 58:     iglobal = i + low;
 59:     v = one*((PetscReal)i) + 100.0*rank;
 60:     VecSetValues(u,1,&iglobal,&v,INSERT_VALUES);
 61:   }
 62:   VecAssemblyBegin(u);
 63:   VecAssemblyEnd(u);

 65:   MatMult(C,u,b);

 67:   VecView(u,PETSC_VIEWER_STDOUT_WORLD);
 68:   VecView(b,PETSC_VIEWER_STDOUT_WORLD);

 70:   VecDestroy(&u);
 71:   VecDestroy(&b);

 73:   PetscOptionsHasName(PETSC_NULL,"-view_info",&flg);
 74:   if (flg)  {PetscViewerSetFormat(PETSC_VIEWER_STDOUT_WORLD,PETSC_VIEWER_ASCII_INFO);}
 75:   MatView(C,PETSC_VIEWER_STDOUT_WORLD);

 77:   MatGetInfo(C,MAT_GLOBAL_SUM,&info);
 78:   PetscPrintf(PETSC_COMM_WORLD,"matrix information (global sums):\n\
 79:      nonzeros = %D, allocated nonzeros = %D\n",(PetscInt)info.nz_used,(PetscInt)info.nz_allocated);
 80:   MatGetInfo (C,MAT_GLOBAL_MAX,&info);
 81:   PetscPrintf(PETSC_COMM_WORLD,"matrix information (global max):\n\
 82:      nonzeros = %D, allocated nonzeros = %D\n",(PetscInt)info.nz_used,(PetscInt)info.nz_allocated);

 84:   MatDestroy(&C);
 85:   PetscFinalize();
 86:   return 0;
 87: }