VecStrideNorm#
Computes the norm of subvector of a vector defined by a starting point and a stride.
Synopsis#
#include "petscvec.h"
PetscErrorCode VecStrideNorm(Vec v, PetscInt start, NormType ntype, PetscReal *nrm)
Collective
Input Parameters#
v - the vector
start - starting point of the subvector (defined by a stride)
ntype - type of norm, one of
NORM_1,NORM_2,NORM_INFINITY
Output Parameter#
norm - the norm
Notes#
One must call VecSetBlockSize() before this routine to set the stride
information, or use a vector created from a multicomponent DMDA.
If x is the array representing the vector x then this computes the norm of the array (x[start],x[start+stride],x[start+2*stride], ….)
This is useful for computing, say the norm of the pressure variable when the pressure is stored (interlaced) with other variables, say density etc.
This will only work if the desire subvector is a stride subvector
See Also#
Vec, VecNorm(), VecStrideGather(), VecStrideScatter(), VecStrideMin(), VecStrideMax()
Level#
advanced
Location#
Examples#
src/ksp/ksp/tutorials/ex42.c
src/ksp/ksp/tutorials/ex43.c
src/snes/tutorials/ex22.c
src/vec/vec/tutorials/ex11.c
src/vec/vec/tutorials/ex11f.F90
src/vec/vec/tutorials/ex11f90.F90
Index of all Vec routines
Table of Contents for all manual pages
Index of all manual pages