#include "petscvec.h" PetscErrorCode VecNorm(Vec x,NormType type,PetscReal *val)Collective on Vec
| x | - the vector | |
| type | - one of NORM_1, NORM_2, NORM_INFINITY. Also available NORM_1_AND_2, which computes both norms and stores them in a two element array. |
NORM_1 denotes sum_i |x_i|
NORM_2 denotes sqrt(sum_i (x_i)^2)
NORM_INFINITY denotes max_i |x_i|
For complex numbers NORM_1 will return the traditional 1 norm of the 2 norm of the complex numbers; that is the 1 norm of the absolutely values of the complex entries. In PETSc 3.6 and earlier releases it returned the 1 norm of the 1 norm of the complex entries (what is returned by the BLAS routine asum()). Both are valid norms but most people expect the former.
per-processor memory bandwidth
interprocessor latency
work load inbalance that causes certain processes to arrive much earlier than others
Level:intermediate
Location:src/vec/vec/interface/rvector.c
Index of all Vec routines
Table of Contents for all manual pages
Index of all manual pages