Actual source code: ex11.c
petsc-3.4.2 2013-07-02

      2: static char help[] = "Demonstrates VecStrideNorm().\n\n";

      4: /*T
      5:    Concepts: vectors^norms of sub-vectors;
      6:    Processors: n
      7: T*/

      9: /*
     10:   Include "petscvec.h" so that we can use vectors.  Note that this file
     11:   automatically includes:
     12:      petscsys.h       - base PETSc routines   petscis.h     - index sets
     13:      petscviewer.h - viewers
     14: */

     16: #include <petscvec.h>

     20: int main(int argc,char **argv)
     21: {
     22:   Vec            x;               /* vectors */
     23:   PetscReal      norm;
     24:   PetscInt       n = 20;
     26:   PetscScalar    one = 1.0;

     28:   PetscInitialize(&argc,&argv,(char*)0,help);
     29:   PetscOptionsGetInt(NULL,"-n",&n,NULL);

     31:   /*
     32:      Create a vector, specifying only its global dimension.
     33:      When using VecCreate(), VecSetSizes() and VecSetFromOptions(),
     34:      the vector format (currently parallel,
     35:      shared, or sequential) is determined at runtime.  Also, the parallel
     36:      partitioning of the vector is determined by PETSc at runtime.

     38:      Routines for creating particular vector types directly are:
     39:         VecCreateSeq() - uniprocessor vector
     40:         VecCreateMPI() - distributed vector, where the user can
     41:                          determine the parallel partitioning
     42:         VecCreateShared() - parallel vector that uses shared memory
     43:                             (available only on the SGI); otherwise,
     44:                             is the same as VecCreateMPI()

     46:      With VecCreate(), VecSetSizes() and VecSetFromOptions() the option
     47:      -vec_type mpi or -vec_type shared causes the
     48:      particular type of vector to be formed.

     50:   */
     51:   VecCreate(PETSC_COMM_WORLD,&x);
     52:   VecSetSizes(x,PETSC_DECIDE,n);
     53:   VecSetBlockSize(x,2);
     54:   VecSetFromOptions(x);

     56:   /*
     57:      Set the vectors to entries to a constant value.
     58:   */
     59:   VecSet(x,one);

     61:   VecNorm(x,NORM_2,&norm);
     62:   PetscPrintf(PETSC_COMM_WORLD,"Norm of entire vector %G\n",norm);

     64:   VecStrideNorm(x,0,NORM_2,&norm);
     65:   PetscPrintf(PETSC_COMM_WORLD,"Norm of sub-vector %G\n",norm);

     67:   VecStrideNorm(x,1,NORM_2,&norm);
     68:   PetscPrintf(PETSC_COMM_WORLD,"Norm of sub-vector %G\n",norm);

     70:   VecStrideNorm(x,1,NORM_1,&norm);
     71:   PetscPrintf(PETSC_COMM_WORLD,"Norm of sub-vector %G\n",norm);

     73:   VecStrideNorm(x,1,NORM_INFINITY,&norm);
     74:   PetscPrintf(PETSC_COMM_WORLD,"Norm of sub-vector %G\n",norm);

     76:   /*
     77:      Free work space.  All PETSc objects should be destroyed when they
     78:      are no longer needed.
     79:   */
     80:   VecDestroy(&x);
     81:   PetscFinalize();
     82:   return 0;
     83: }