VecSetValues#

Inserts or adds values into certain locations of a vector.

Synopsis#

#include "petscvec.h"   
PetscErrorCode VecSetValues(Vec x, PetscInt ni, const PetscInt ix[], const PetscScalar y[], InsertMode iora)

Not Collective

Input Parameters#

x - vector to insert in
ni - number of elements to add
ix - indices where to add
y - array of values
iora - either INSERT_VALUES to replace the current values or ADD_VALUES to add values to any existing entries

Notes#

   `VecSetValues()` sets x[ix[i]] = y[i], for i=0,...,ni-1.

Calls to VecSetValues() with the INSERT_VALUES and ADD_VALUES options cannot be mixed without intervening calls to the assembly routines.

These values may be cached, so VecAssemblyBegin() and VecAssemblyEnd() MUST be called after all calls to VecSetValues() have been completed.

VecSetValues() uses 0-based indices in Fortran as well as in C.

If you call VecSetOption(x, VEC_IGNORE_NEGATIVE_INDICES,PETSC_TRUE), negative indices may be passed in ix. These rows are simply ignored. This allows easily inserting element load matrices with homogeneous Dirichlet boundary conditions that you don’t want represented in the vector.