static PetscErrorCode TSStage_EIMEX(TS ts,PetscInt istage)
{
TS_EIMEX *ext = (TS_EIMEX*)ts->data;
PetscReal h;
Vec Y=ext->Y, Z=ext->Z;
SNES snes;
TSAdapt adapt;
PetscInt i,its,lits;
PetscBool accept;
PetscErrorCode ierr;
PetscFunctionBegin;
ierr = TSGetSNES(ts,&snes);CHKERRQ(ierr);
h = ts->time_step/ext->N[istage];/* step size for the istage-th stage */
ext->shift = 1./h;
ierr = SNESSetLagJacobian(snes,-2);CHKERRQ(ierr); /* Recompute the Jacobian on this solve, but not again */
ierr = VecCopy(ext->VecSolPrev,Y);CHKERRQ(ierr); /* Take the previous solution as intial step */
for(i=0; i<ext->N[istage]; i++){
ext->ctime = ts->ptime + h*i;
ierr = VecCopy(Y,Z);CHKERRQ(ierr);/* Save the solution of the previous substep */
ierr = SNESSolve(snes,NULL,Y);CHKERRQ(ierr);
ierr = SNESGetIterationNumber(snes,&its);CHKERRQ(ierr);
ierr = SNESGetLinearSolveIterations(snes,&lits);CHKERRQ(ierr);
ts->snes_its += its; ts->ksp_its += lits;
ierr = TSGetAdapt(ts,&adapt);CHKERRQ(ierr);
ierr = TSAdaptCheckStage(adapt,ts,ext->ctime,Y,&accept);CHKERRQ(ierr);
}
PetscFunctionReturn(0);
}
void VentilationProblem::SolveFromPressureWithSnes()
{
assert( !mFluxGivenAtInflow ); // It's not a direct solve
if (mTerminalInteractionMatrix == NULL)
{
SetupIterativeSolver();
}
SNES snes;
SNESCreate(PETSC_COMM_SELF, &snes);
// Set the residual creation function (direct solve flux->pressure followed by pressure matching)
SNESSetFunction(snes, mTerminalPressureChangeVector /*residual*/ , &ComputeSnesResidual, this);
// The approximate Jacobian has been precomputed so we are going to wing it
SNESSetJacobian(snes, mTerminalInteractionMatrix, mTerminalInteractionMatrix, /*&ComputeSnesJacobian*/ NULL, this);
#if (PETSC_VERSION_MAJOR == 3) //PETSc 3.x
SNESSetLagJacobian(snes, -1 /*Never rebuild Jacobian*/);
#else
SNESSetType(snes, SNESLS);
#endif
#if (PETSC_VERSION_MAJOR == 3 && PETSC_VERSION_MINOR >= 4) //PETSc 3.4 or later
SNESSetType(snes, SNESNEWTONLS);
#else
SNESSetType(snes, SNESLS);
#endif
// Set the relative tolerance on the residual
// Also set the absolute tolerance - useful for when the solver is started from the correct answer
SNESSetTolerances(snes, 1.0e-16/*abs_tol*/, 1e-15/*r_tol*/, PETSC_DEFAULT/*step_tol*/, PETSC_DEFAULT, PETSC_DEFAULT);
#if (PETSC_VERSION_MAJOR == 3 && PETSC_VERSION_MINOR == 3) //PETSc 3.3
SNESLineSearch linesearch;
SNESGetSNESLineSearch(snes, &linesearch);
SNESLineSearchSetType(linesearch, "bt"); //Use backtracking search as default
#elif (PETSC_VERSION_MAJOR == 3 && PETSC_VERSION_MINOR >= 4) //PETSc 3.4 or later
SNESLineSearch linesearch;
SNESGetLineSearch(snes, &linesearch);
SNESLineSearchSetType(linesearch, "bt"); //Use backtracking search as default
#endif
SNESSetFromOptions(snes);
#if (PETSC_VERSION_MAJOR == 3 && PETSC_VERSION_MINOR >= 5)
// Seems to want the preconditioner to be explicitly set to none now
// Copied this from the similar PETSc example at:
// http://www.mcs.anl.gov/petsc/petsc-current/src/snes/examples/tutorials/ex1.c
// Which got it to work...
KSP ksp;
SNESGetKSP(snes,&ksp);
PC pc;
KSPGetPC(ksp,&pc);
PCSetType(pc,PCNONE);
#endif
#if (PETSC_VERSION_MAJOR == 2 && PETSC_VERSION_MINOR == 2) //PETSc 2.2
SNESSolve(snes, mTerminalFluxChangeVector);
#else
SNESSolve(snes, PETSC_NULL, mTerminalFluxChangeVector);
#endif
///\todo #2300 If used with time-stepping we should maintain a permanent SNES object
SNESDestroy(PETSC_DESTROY_PARAM(snes));
}
