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

  3: /*
  4:   Include "petscvec.h" so that we can use vectors.  Note that this file
  5:   automatically includes:
  6:      petscsys.h       - base PETSc routines   petscis.h     - index sets
  7:      petscviewer.h - viewers
  8: */

 10: #include <petscvec.h>

 12: int main(int argc, char **argv)
 13: {
 14:   Vec         x; /* vectors */
 15:   PetscReal   norm;
 16:   PetscInt    n   = 20;
 17:   PetscScalar one = 1.0;

 19:   PetscFunctionBeginUser;
 20:   PetscCall(PetscInitialize(&argc, &argv, (char *)0, help));
 21:   PetscCall(PetscOptionsGetInt(NULL, NULL, "-n", &n, NULL));

 23:   /*
 24:      Create a vector, specifying only its global dimension.
 25:      When using VecCreate(), VecSetSizes() and VecSetFromOptions(),
 26:      the vector format (currently parallel,
 27:      shared, or sequential) is determined at runtime.  Also, the parallel
 28:      partitioning of the vector is determined by PETSc at runtime.
 29:   */
 30:   PetscCall(VecCreate(PETSC_COMM_WORLD, &x));
 31:   PetscCall(VecSetSizes(x, PETSC_DECIDE, n));
 32:   PetscCall(VecSetBlockSize(x, 2));
 33:   PetscCall(VecSetFromOptions(x));

 35:   /*
 36:      Set the vectors to entries to a constant value.
 37:   */
 38:   PetscCall(VecSet(x, one));

 40:   PetscCall(VecNorm(x, NORM_2, &norm));
 41:   PetscCall(PetscPrintf(PETSC_COMM_WORLD, "L_2 Norm of entire vector: %g\n", (double)norm));

 43:   PetscCall(VecNorm(x, NORM_1, &norm));
 44:   PetscCall(PetscPrintf(PETSC_COMM_WORLD, "L_1 Norm of entire vector: %g\n", (double)norm));

 46:   PetscCall(VecNorm(x, NORM_INFINITY, &norm));
 47:   PetscCall(PetscPrintf(PETSC_COMM_WORLD, "L_inf Norm of entire vector: %g\n", (double)norm));

 49:   PetscCall(VecStrideNorm(x, 0, NORM_2, &norm));
 50:   PetscCall(PetscPrintf(PETSC_COMM_WORLD, "L_2 Norm of sub-vector 0: %g\n", (double)norm));

 52:   PetscCall(VecStrideNorm(x, 0, NORM_1, &norm));
 53:   PetscCall(PetscPrintf(PETSC_COMM_WORLD, "L_1 Norm of sub-vector 0: %g\n", (double)norm));

 55:   PetscCall(VecStrideNorm(x, 0, NORM_INFINITY, &norm));
 56:   PetscCall(PetscPrintf(PETSC_COMM_WORLD, "L_inf Norm of sub-vector 0: %g\n", (double)norm));

 58:   PetscCall(VecStrideNorm(x, 1, NORM_2, &norm));
 59:   PetscCall(PetscPrintf(PETSC_COMM_WORLD, "L_2 Norm of sub-vector 1: %g\n", (double)norm));

 61:   PetscCall(VecStrideNorm(x, 1, NORM_1, &norm));
 62:   PetscCall(PetscPrintf(PETSC_COMM_WORLD, "L_1 Norm of sub-vector 1: %g\n", (double)norm));

 64:   PetscCall(VecStrideNorm(x, 1, NORM_INFINITY, &norm));
 65:   PetscCall(PetscPrintf(PETSC_COMM_WORLD, "L_inf Norm of sub-vector 1: %g\n", (double)norm));

 67:   /*
 68:      Free work space.  All PETSc objects should be destroyed when they
 69:      are no longer needed.
 70:   */
 71:   PetscCall(VecDestroy(&x));
 72:   PetscCall(PetscFinalize());
 73:   return 0;
 74: }

 76: /*TEST

 78:      test:
 79:        nsize: 2

 81: TEST*/