petsc-3.3-p7 2013-05-11

VecStrideNormAll

Computes the norms subvectors of a vector defined by a starting point and a stride.

#include "petscvec.h" 
PetscErrorCode  VecStrideNormAll(Vec v,NormType ntype,PetscReal nrm[])

Collective on Vec

	v	- the vector
	ntype	- type of norm, one of NORM_1, NORM_2, NORM_INFINITY

nrm -the norms

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