# PetscObjectStateIncrease#

Increases the state of any PetscObject

## Synopsis#

#include "petsc/private/petscimpl.h"
PetscErrorCode PetscObjectStateIncrease(PetscObject obj)


Logically Collective

## Input Parameter#

• obj - any PETSc object, for example a Vec, Mat or KSP. This must be cast with a (PetscObject), for example, PetscObjectStateIncrease((PetscObject)mat);

## Notes#

Object state is a 64 bit integer which gets increased every time the object is changed internally. By saving and later querying the object state one can determine whether information about the object is still current. Currently, state is maintained for Vec and Mat objects.

This routine is mostly for internal use by PETSc; a developer need only call it after explicit access to an object’s internals. Routines such as VecSet() or MatScale() already call this routine. It is also called, as a precaution, in VecRestoreArray(), MatRestoreRow(), MatDenseRestoreArray().

Routines such as VecNorm() can by-pass the computation if the norm has already been computed and the vector’s state has not changed.

This routine is logically collective because state equality comparison needs to be possible without communication.

Mat also has MatGetNonzeroState() and MatSetNonzeroState() for tracking changes to the nonzero structure.

PetscObjectStateGet(), MatSetNonzeroState(), PetscObject

developer

## Location#

include/petsc/private/petscimpl.h

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