TSPruneIJacobianColor

Remove nondiagonal zeros in the Jacobian matrix and update the MatMFFD coloring information.

Synopsis

#include "petscts.h"  
PetscErrorCode TSPruneIJacobianColor(TS ts, Mat J, Mat B)

Collective

Input Parameters

• ts - the TS context

• J - Jacobian matrix (not altered in this routine)

• B - newly computed Jacobian matrix to use with preconditioner

Notes

This function improves the MatFDColoring performance when the Jacobian matrix was over-allocated or contains many constant zeros entries, which is typically the case when the matrix is generated by a DM and multiple fields are involved.

Users need to make sure that the Jacobian matrix is properly filled to reflect the sparsity structure. For MatFDColoring, the values of nonzero entries are not important. So one can usually call TSComputeIJacobian() with randomized input vectors to generate a dummy Jacobian. TSComputeIJacobian() should be called before TSSolve() but after TSSetUp().

See Also

TS: Scalable ODE and DAE Solvers, TS, MatFDColoring, TSComputeIJacobianDefaultColor(), MatEliminateZeros(), MatFDColoringCreate(), MatFDColoringSetFunction()

Level

intermediate

Location

src/ts/interface/ts.c

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