petsc-3.6.1 2015-08-06

TSComputeIJacobianConstant

Reuses a time-independent for a semi-implicit DAE or ODE

Synopsis

#include "petscts.h"  
PetscErrorCode TSComputeIJacobianConstant(TS ts,PetscReal t,Vec U,Vec Udot,PetscReal shift,Mat A,Mat B,void *ctx)

Collective on TS

Input Arguments

	ts	- time stepping context
	t	- time at which to evaluate
	U	- state at which to evaluate
	Udot	- time derivative of state vector
	shift	- shift to apply
	ctx	- context

Output Arguments

	A	- pointer to operator
	B	- pointer to preconditioning matrix
	flg	- matrix structure flag

Notes

This function is intended to be passed to TSSetIJacobian() to evaluate the Jacobian for linear time-independent problems.

It is only appropriate for problems of the form

    M Udot = F(U,t)

where M is constant and F is non-stiff. The user must pass M to TSSetIJacobian(). The current implementation only works with IMEX time integration methods such as TSROSW and TSARKIMEX, since there is no support for de-constructing an implicit operator of the form

   shift*M + J

where J is the Jacobian of -F(U). Support may be added in a future version of PETSc, but for now, the user must store a copy of M or reassemble it when requested.

TSComputeIJacobianConstant

Synopsis

Input Arguments

Output Arguments

Notes

See Also