/*
* This is a modified version of PETSc/src/ts/examples/tutorials/ex15.c
* to demonstrate how MOOSE interact with an external solver package
*/
PetscErrorCode
externalPETScDiffusionFDMSolve(TS ts, Vec u, PetscReal dt, PetscReal time)
{
PetscErrorCode ierr;
#if !PETSC_VERSION_LESS_THAN(3, 8, 0)
PetscInt current_step;
#endif
DM da;
PetscFunctionBeginUser;
ierr = TSGetDM(ts, &da);
CHKERRQ(ierr);
#if !PETSC_VERSION_LESS_THAN(3, 7, 0)
PetscOptionsSetValue(NULL, "-ts_monitor", NULL);
PetscOptionsSetValue(NULL, "-snes_monitor", NULL);
PetscOptionsSetValue(NULL, "-ksp_monitor", NULL);
#else
PetscOptionsSetValue("-ts_monitor", NULL);
PetscOptionsSetValue("-snes_monitor", NULL);
PetscOptionsSetValue("-ksp_monitor", NULL);
#endif
/*ierr = TSSetMaxTime(ts,1.0);CHKERRQ(ierr);*/
ierr = TSSetExactFinalTime(ts, TS_EXACTFINALTIME_STEPOVER);
CHKERRQ(ierr);
ierr = TSSetSolution(ts, u);
CHKERRQ(ierr);
ierr = TSSetTimeStep(ts, dt);
CHKERRQ(ierr);
ierr = TSSetTime(ts, time - dt);
CHKERRQ(ierr);
#if !PETSC_VERSION_LESS_THAN(3, 8, 0)
ierr = TSGetStepNumber(ts, ¤t_step);
CHKERRQ(ierr);
ierr = TSSetMaxSteps(ts, current_step + 1);
CHKERRQ(ierr);
#else
SETERRQ(PetscObjectComm((PetscObject)ts), PETSC_ERR_SUP, "Require PETSc-3.8.x or higher ");
#endif
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Sets various TS parameters from user options
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
ierr = TSSetFromOptions(ts);
CHKERRQ(ierr);
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Solve nonlinear system
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
ierr = TSSolve(ts, u);
CHKERRQ(ierr);
PetscFunctionReturn(0);
}
int main(int argc,char **argv)
{
AppCtx appctx; /* user-defined application context */
PetscErrorCode ierr;
PetscInt i, xs, xm, ind, j, lenglob;
PetscReal x, *wrk_ptr1, *wrk_ptr2;
MatNullSpace nsp;
PetscMPIInt size;
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Initialize program and set problem parameters
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
PetscFunctionBegin;
ierr = PetscInitialize(&argc,&argv,(char*)0,help);if (ierr) return ierr;
/*initialize parameters */
appctx.param.N = 10; /* order of the spectral element */
appctx.param.E = 10; /* number of elements */
appctx.param.L = 4.0; /* length of the domain */
appctx.param.mu = 0.01; /* diffusion coefficient */
appctx.initial_dt = 5e-3;
appctx.param.steps = PETSC_MAX_INT;
appctx.param.Tend = 4;
ierr = PetscOptionsGetInt(NULL,NULL,"-N",&appctx.param.N,NULL);CHKERRQ(ierr);
ierr = PetscOptionsGetInt(NULL,NULL,"-E",&appctx.param.E,NULL);CHKERRQ(ierr);
ierr = PetscOptionsGetReal(NULL,NULL,"-Tend",&appctx.param.Tend,NULL);CHKERRQ(ierr);
ierr = PetscOptionsGetReal(NULL,NULL,"-mu",&appctx.param.mu,NULL);CHKERRQ(ierr);
appctx.param.Le = appctx.param.L/appctx.param.E;
ierr = MPI_Comm_size(PETSC_COMM_WORLD,&size);CHKERRQ(ierr);
if (appctx.param.E % size) SETERRQ(PETSC_COMM_WORLD,PETSC_ERR_ARG_WRONG,"Number of elements must be divisible by number of processes");
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Create GLL data structures
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
ierr = PetscGLLCreate(appctx.param.N,PETSCGLL_VIA_LINEARALGEBRA,&appctx.SEMop.gll);CHKERRQ(ierr);
lenglob = appctx.param.E*(appctx.param.N-1);
/*
Create distributed array (DMDA) to manage parallel grid and vectors
and to set up the ghost point communication pattern. There are E*(Nl-1)+1
total grid values spread equally among all the processors, except first and last
*/
ierr = DMDACreate1d(PETSC_COMM_WORLD,DM_BOUNDARY_PERIODIC,lenglob,1,1,NULL,&appctx.da);CHKERRQ(ierr);
ierr = DMSetFromOptions(appctx.da);CHKERRQ(ierr);
ierr = DMSetUp(appctx.da);CHKERRQ(ierr);
/*
Extract global and local vectors from DMDA; we use these to store the
approximate solution. Then duplicate these for remaining vectors that
have the same types.
*/
ierr = DMCreateGlobalVector(appctx.da,&appctx.dat.curr_sol);CHKERRQ(ierr);
ierr = VecDuplicate(appctx.dat.curr_sol,&appctx.SEMop.grid);CHKERRQ(ierr);
ierr = VecDuplicate(appctx.dat.curr_sol,&appctx.SEMop.mass);CHKERRQ(ierr);
ierr = DMDAGetCorners(appctx.da,&xs,NULL,NULL,&xm,NULL,NULL);CHKERRQ(ierr);
ierr = DMDAVecGetArray(appctx.da,appctx.SEMop.grid,&wrk_ptr1);CHKERRQ(ierr);
ierr = DMDAVecGetArray(appctx.da,appctx.SEMop.mass,&wrk_ptr2);CHKERRQ(ierr);
/* Compute function over the locally owned part of the grid */
xs=xs/(appctx.param.N-1);
xm=xm/(appctx.param.N-1);
/*
Build total grid and mass over entire mesh (multi-elemental)
*/
for (i=xs; i<xs+xm; i++) {
for (j=0; j<appctx.param.N-1; j++) {
x = (appctx.param.Le/2.0)*(appctx.SEMop.gll.nodes[j]+1.0)+appctx.param.Le*i;
ind=i*(appctx.param.N-1)+j;
wrk_ptr1[ind]=x;
wrk_ptr2[ind]=.5*appctx.param.Le*appctx.SEMop.gll.weights[j];
if (j==0) wrk_ptr2[ind]+=.5*appctx.param.Le*appctx.SEMop.gll.weights[j];
}
}
ierr = DMDAVecRestoreArray(appctx.da,appctx.SEMop.grid,&wrk_ptr1);CHKERRQ(ierr);
ierr = DMDAVecRestoreArray(appctx.da,appctx.SEMop.mass,&wrk_ptr2);CHKERRQ(ierr);
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Create matrix data structure; set matrix evaluation routine.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
ierr = DMSetMatrixPreallocateOnly(appctx.da, PETSC_TRUE);CHKERRQ(ierr);
ierr = DMCreateMatrix(appctx.da,&appctx.SEMop.stiff);CHKERRQ(ierr);
ierr = DMCreateMatrix(appctx.da,&appctx.SEMop.grad);CHKERRQ(ierr);
/*
For linear problems with a time-dependent f(u,t) in the equation
u_t = f(u,t), the user provides the discretized right-hand-side
as a time-dependent matrix.
*/
ierr = RHSMatrixLaplaciangllDM(appctx.ts,0.0,appctx.dat.curr_sol,appctx.SEMop.stiff,appctx.SEMop.stiff,&appctx);CHKERRQ(ierr);
ierr = RHSMatrixAdvectiongllDM(appctx.ts,0.0,appctx.dat.curr_sol,appctx.SEMop.grad,appctx.SEMop.grad,&appctx);CHKERRQ(ierr);
/*
For linear problems with a time-dependent f(u,t) in the equation
u_t = f(u,t), the user provides the discretized right-hand-side
as a time-dependent matrix.
*/
ierr = MatDuplicate(appctx.SEMop.stiff,MAT_COPY_VALUES,&appctx.SEMop.keptstiff);CHKERRQ(ierr);
/* attach the null space to the matrix, this probably is not needed but does no harm */
ierr = MatNullSpaceCreate(PETSC_COMM_WORLD,PETSC_TRUE,0,NULL,&nsp);CHKERRQ(ierr);
ierr = MatSetNullSpace(appctx.SEMop.stiff,nsp);CHKERRQ(ierr);
ierr = MatSetNullSpace(appctx.SEMop.keptstiff,nsp);CHKERRQ(ierr);
ierr = MatNullSpaceTest(nsp,appctx.SEMop.stiff,NULL);CHKERRQ(ierr);
ierr = MatNullSpaceDestroy(&nsp);CHKERRQ(ierr);
/* attach the null space to the matrix, this probably is not needed but does no harm */
ierr = MatNullSpaceCreate(PETSC_COMM_WORLD,PETSC_TRUE,0,NULL,&nsp);CHKERRQ(ierr);
ierr = MatSetNullSpace(appctx.SEMop.grad,nsp);CHKERRQ(ierr);
ierr = MatNullSpaceTest(nsp,appctx.SEMop.grad,NULL);CHKERRQ(ierr);
ierr = MatNullSpaceDestroy(&nsp);CHKERRQ(ierr);
/* Create the TS solver that solves the ODE and its adjoint; set its options */
ierr = TSCreate(PETSC_COMM_WORLD,&appctx.ts);CHKERRQ(ierr);
ierr = TSSetProblemType(appctx.ts,TS_NONLINEAR);CHKERRQ(ierr);
ierr = TSSetType(appctx.ts,TSRK);CHKERRQ(ierr);
ierr = TSSetDM(appctx.ts,appctx.da);CHKERRQ(ierr);
ierr = TSSetTime(appctx.ts,0.0);CHKERRQ(ierr);
ierr = TSSetTimeStep(appctx.ts,appctx.initial_dt);CHKERRQ(ierr);
ierr = TSSetMaxSteps(appctx.ts,appctx.param.steps);CHKERRQ(ierr);
ierr = TSSetMaxTime(appctx.ts,appctx.param.Tend);CHKERRQ(ierr);
ierr = TSSetExactFinalTime(appctx.ts,TS_EXACTFINALTIME_MATCHSTEP);CHKERRQ(ierr);
ierr = TSSetTolerances(appctx.ts,1e-7,NULL,1e-7,NULL);CHKERRQ(ierr);
ierr = TSSetSaveTrajectory(appctx.ts);CHKERRQ(ierr);
ierr = TSSetFromOptions(appctx.ts);CHKERRQ(ierr);
ierr = TSSetRHSFunction(appctx.ts,NULL,RHSFunction,&appctx);CHKERRQ(ierr);
ierr = TSSetRHSJacobian(appctx.ts,appctx.SEMop.stiff,appctx.SEMop.stiff,RHSJacobian,&appctx);CHKERRQ(ierr);
/* Set Initial conditions for the problem */
ierr = TrueSolution(appctx.ts,0,appctx.dat.curr_sol,&appctx);CHKERRQ(ierr);
ierr = TSSetSolutionFunction(appctx.ts,(PetscErrorCode (*)(TS,PetscReal,Vec,void *))TrueSolution,&appctx);CHKERRQ(ierr);
ierr = TSSetTime(appctx.ts,0.0);CHKERRQ(ierr);
ierr = TSSetStepNumber(appctx.ts,0);CHKERRQ(ierr);
ierr = TSSolve(appctx.ts,appctx.dat.curr_sol);CHKERRQ(ierr);
ierr = MatDestroy(&appctx.SEMop.stiff);CHKERRQ(ierr);
ierr = MatDestroy(&appctx.SEMop.keptstiff);CHKERRQ(ierr);
ierr = MatDestroy(&appctx.SEMop.grad);CHKERRQ(ierr);
ierr = VecDestroy(&appctx.SEMop.grid);CHKERRQ(ierr);
ierr = VecDestroy(&appctx.SEMop.mass);CHKERRQ(ierr);
ierr = VecDestroy(&appctx.dat.curr_sol);CHKERRQ(ierr);
ierr = PetscGLLDestroy(&appctx.SEMop.gll);CHKERRQ(ierr);
ierr = DMDestroy(&appctx.da);CHKERRQ(ierr);
ierr = TSDestroy(&appctx.ts);CHKERRQ(ierr);
/*
Always call PetscFinalize() before exiting a program. This routine
- finalizes the PETSc libraries as well as MPI
- provides summary and diagnostic information if certain runtime
options are chosen (e.g., -log_summary).
*/
ierr = PetscFinalize();
return ierr;
}
/*
* time_step solves for the time_dependence of the system
* that was previously setup using the add_to_ham and add_lin
* routines. Solver selection and parameters can be controlled via PETSc
* command line options. Default solver is TSRK3BS
*
* Inputs:
* Vec x: The density matrix, with appropriate inital conditions
* double dt: initial timestep. For certain explicit methods, this timestep
* can be changed, as those methods have adaptive time steps
* double time_max: the maximum time to integrate to
* int steps_max: max number of steps to take
*/
void time_step(Vec x, PetscReal init_time, PetscReal time_max,PetscReal dt,PetscInt steps_max){
PetscViewer mat_view;
TS ts; /* timestepping context */
PetscInt i,j,Istart,Iend,steps,row,col;
PetscScalar mat_tmp;
PetscReal tmp_real;
Mat AA;
PetscInt nevents,direction;
PetscBool terminate;
operator op;
int num_pop;
double *populations;
Mat solve_A,solve_stiff_A;
PetscLogStagePop();
PetscLogStagePush(solve_stage);
if (_lindblad_terms) {
if (nid==0) {
printf("Lindblad terms found, using Lindblad solver.\n");
}
solve_A = full_A;
if (_stiff_solver) {
if(nid==0) printf("ERROR! Lindblad-stiff solver untested.");
exit(0);
}
} else {
if (nid==0) {
printf("No Lindblad terms found, using (more efficient) Schrodinger solver.\n");
}
solve_A = ham_A;
solve_stiff_A = ham_stiff_A;
if (_num_time_dep&&_stiff_solver) {
if(nid==0) printf("ERROR! Schrodinger-stiff + timedep solver untested.");
exit(0);
}
}
/* Possibly print dense ham. No stabilization is needed? */
if (nid==0) {
/* Print dense ham, if it was asked for */
if (_print_dense_ham){
FILE *fp_ham;
fp_ham = fopen("ham","w");
if (nid==0){
for (i=0;i<total_levels;i++){
for (j=0;j<total_levels;j++){
fprintf(fp_ham,"%e %e ",PetscRealPart(_hamiltonian[i][j]),PetscImaginaryPart(_hamiltonian[i][j]));
}
fprintf(fp_ham,"\n");
}
}
fclose(fp_ham);
for (i=0;i<total_levels;i++){
free(_hamiltonian[i]);
}
free(_hamiltonian);
_print_dense_ham = 0;
}
}
/* Remove stabilization if it was previously added */
if (stab_added){
if (nid==0) printf("Removing stabilization...\n");
/*
* We add 1.0 in the 0th spot and every n+1 after
*/
if (nid==0) {
row = 0;
for (i=0;i<total_levels;i++){
col = i*(total_levels+1);
mat_tmp = -1.0 + 0.*PETSC_i;
MatSetValue(full_A,row,col,mat_tmp,ADD_VALUES);
}
}
}
MatGetOwnershipRange(solve_A,&Istart,&Iend);
/*
* Explicitly add 0.0 to all diagonal elements;
* this fixes a 'matrix in wrong state' message that PETSc
* gives if the diagonal was never initialized.
*/
//if (nid==0) printf("Adding 0 to diagonal elements...\n");
for (i=Istart;i<Iend;i++){
mat_tmp = 0 + 0.*PETSC_i;
MatSetValue(solve_A,i,i,mat_tmp,ADD_VALUES);
}
if(_stiff_solver){
MatGetOwnershipRange(solve_stiff_A,&Istart,&Iend);
for (i=Istart;i<Iend;i++){
mat_tmp = 0 + 0.*PETSC_i;
MatSetValue(solve_stiff_A,i,i,mat_tmp,ADD_VALUES);
}
}
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -*
* Create the timestepping solver and set various options *
*- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
/*
* Create timestepping solver context
*/
TSCreate(PETSC_COMM_WORLD,&ts);
TSSetProblemType(ts,TS_LINEAR);
/*
* Set function to get information at every timestep
*/
if (_ts_monitor!=NULL){
TSMonitorSet(ts,_ts_monitor,_tsctx,NULL);
}
/*
* Set up ODE system
*/
TSSetRHSFunction(ts,NULL,TSComputeRHSFunctionLinear,NULL);
if(_stiff_solver) {
/* TSSetIFunction(ts,NULL,TSComputeRHSFunctionLinear,NULL); */
if (nid==0) {
printf("Stiff solver not implemented!\n");
exit(0);
}
if(nid==0) printf("Using stiff solver - TSROSW\n");
}
if(_num_time_dep+_num_time_dep_lin) {
for(i=0;i<_num_time_dep;i++){
tmp_real = 0.0;
_add_ops_to_mat_ham(tmp_real,solve_A,_time_dep_list[i].num_ops,_time_dep_list[i].ops);
}
for(i=0;i<_num_time_dep_lin;i++){
tmp_real = 0.0;
_add_ops_to_mat_lin(tmp_real,solve_A,_time_dep_list_lin[i].num_ops,_time_dep_list_lin[i].ops);
}
/* Tell PETSc to assemble the matrix */
MatAssemblyBegin(solve_A,MAT_FINAL_ASSEMBLY);
MatAssemblyEnd(solve_A,MAT_FINAL_ASSEMBLY);
if (nid==0) printf("Matrix Assembled.\n");
MatDuplicate(solve_A,MAT_COPY_VALUES,&AA);
MatAssemblyBegin(AA,MAT_FINAL_ASSEMBLY);
MatAssemblyEnd(AA,MAT_FINAL_ASSEMBLY);
TSSetRHSJacobian(ts,AA,AA,_RHS_time_dep_ham_p,NULL);
} else {
/* Tell PETSc to assemble the matrix */
MatAssemblyBegin(solve_A,MAT_FINAL_ASSEMBLY);
MatAssemblyEnd(solve_A,MAT_FINAL_ASSEMBLY);
if (_stiff_solver){
MatAssemblyBegin(solve_stiff_A,MAT_FINAL_ASSEMBLY);
MatAssemblyEnd(solve_stiff_A,MAT_FINAL_ASSEMBLY);
/* TSSetIJacobian(ts,solve_stiff_A,solve_stiff_A,TSComputeRHSJacobianConstant,NULL); */
if (nid==0) {
printf("Stiff solver not implemented!\n");
exit(0);
}
}
if (nid==0) printf("Matrix Assembled.\n");
TSSetRHSJacobian(ts,solve_A,solve_A,TSComputeRHSJacobianConstant,NULL);
}
/* Print information about the matrix. */
PetscViewerASCIIOpen(PETSC_COMM_WORLD,NULL,&mat_view);
PetscViewerPushFormat(mat_view,PETSC_VIEWER_ASCII_INFO);
/* PetscViewerPushFormat(mat_view,PETSC_VIEWER_ASCII_MATLAB); */
/* MatView(solve_A,mat_view); */
/* PetscInt ncols; */
/* const PetscInt *cols; */
/* const PetscScalar *vals; */
/* for(i=0;i<total_levels*total_levels;i++){ */
/* MatGetRow(solve_A,i,&ncols,&cols,&vals); */
/* for (j=0;j<ncols;j++){ */
/* if(PetscAbsComplex(vals[j])>1e-5){ */
/* printf("%d %d %lf %lf\n",i,cols[j],vals[j]); */
/* } */
/* } */
/* MatRestoreRow(solve_A,i,&ncols,&cols,&vals); */
/* } */
if(_stiff_solver){
MatView(solve_stiff_A,mat_view);
}
PetscViewerPopFormat(mat_view);
PetscViewerDestroy(&mat_view);
TSSetTimeStep(ts,dt);
/*
* Set default options, can be changed at runtime
*/
TSSetMaxSteps(ts,steps_max);
TSSetMaxTime(ts,time_max);
TSSetTime(ts,init_time);
TSSetExactFinalTime(ts,TS_EXACTFINALTIME_STEPOVER);
if (_stiff_solver) {
TSSetType(ts,TSROSW);
} else {
TSSetType(ts,TSRK);
TSRKSetType(ts,TSRK3BS);
}
/* If we have gates to apply, set up the event handler. */
if (_num_quantum_gates > 0) {
nevents = 1; //Only one event for now (did we cross a gate?)
direction = -1; //We only want to count an event if we go from positive to negative
terminate = PETSC_FALSE; //Keep time stepping after we passed our event
/* Arguments are: ts context, nevents, direction of zero crossing, whether to terminate,
* a function to check event status, a function to apply events, private data context.
*/
TSSetEventHandler(ts,nevents,&direction,&terminate,_QG_EventFunction,_QG_PostEventFunction,NULL);
}
if (_num_circuits > 0) {
nevents = 1; //Only one event for now (did we cross a gate?)
direction = -1; //We only want to count an event if we go from positive to negative
terminate = PETSC_FALSE; //Keep time stepping after we passed our event
/* Arguments are: ts context, nevents, direction of zero crossing, whether to terminate,
* a function to check event status, a function to apply events, private data context.
*/
TSSetEventHandler(ts,nevents,&direction,&terminate,_QC_EventFunction,_QC_PostEventFunction,NULL);
}
if (_discrete_ec > 0) {
nevents = 1; //Only one event for now (did we cross an ec step?)
direction = -1; //We only want to count an event if we go from positive to negative
terminate = PETSC_FALSE; //Keep time stepping after we passed our event
/* Arguments are: ts context, nevents, direction of zero crossing, whether to terminate,
* a function to check event status, a function to apply events, private data context.
*/
TSSetEventHandler(ts,nevents,&direction,&terminate,_DQEC_EventFunction,_DQEC_PostEventFunction,NULL);
}
/* if (_lindblad_terms) { */
/* nevents = 1; //Only one event for now (did we cross a gate?) */
/* direction = 0; //We only want to count an event if we go from positive to negative */
/* terminate = PETSC_FALSE; //Keep time stepping after we passed our event */
/* TSSetEventHandler(ts,nevents,&direction,&terminate,_Normalize_EventFunction,_Normalize_PostEventFunction,NULL); */
/* } */
TSSetFromOptions(ts);
TSSolve(ts,x);
TSGetStepNumber(ts,&steps);
num_pop = get_num_populations();
populations = malloc(num_pop*sizeof(double));
get_populations(x,&populations);
/* if(nid==0){ */
/* printf("Final populations: "); */
/* for(i=0;i<num_pop;i++){ */
/* printf(" %e ",populations[i]); */
/* } */
/* printf("\n"); */
/* } */
/* PetscPrintf(PETSC_COMM_WORLD,"Steps %D\n",steps); */
/* Free work space */
TSDestroy(&ts);
if(_num_time_dep+_num_time_dep_lin){
MatDestroy(&AA);
}
free(populations);
PetscLogStagePop();
PetscLogStagePush(post_solve_stage);
return;
}
int main(int argc,char **argv)
{
AppCtx appctx; /* user-defined application context */
TS ts; /* timestepping context */
Vec U; /* approximate solution vector */
PetscErrorCode ierr;
PetscReal dt;
DM da;
PetscInt M;
PetscMPIInt rank;
PetscBool useLaxWendroff = PETSC_TRUE;
/* Initialize program and set problem parameters */
ierr = PetscInitialize(&argc,&argv,(char*)0,help);if (ierr) return ierr;
ierr = MPI_Comm_rank(PETSC_COMM_WORLD,&rank);CHKERRQ(ierr);
appctx.a = -1.0;
ierr = PetscOptionsGetReal(NULL,NULL,"-a",&appctx.a,NULL);CHKERRQ(ierr);
ierr = DMDACreate1d(PETSC_COMM_WORLD,DM_BOUNDARY_PERIODIC, 60, 1, 1,NULL,&da);CHKERRQ(ierr);
ierr = DMSetFromOptions(da);CHKERRQ(ierr);
ierr = DMSetUp(da);CHKERRQ(ierr);
/* Create vector data structures for approximate and exact solutions */
ierr = DMCreateGlobalVector(da,&U);CHKERRQ(ierr);
/* Create timestepping solver context */
ierr = TSCreate(PETSC_COMM_WORLD,&ts);CHKERRQ(ierr);
ierr = TSSetDM(ts,da);CHKERRQ(ierr);
/* Function evaluation */
ierr = PetscOptionsGetBool(NULL,NULL,"-useLaxWendroff",&useLaxWendroff,NULL);CHKERRQ(ierr);
if (useLaxWendroff) {
if (!rank) {
ierr = PetscPrintf(PETSC_COMM_SELF,"... Use Lax-Wendroff finite volume\n");CHKERRQ(ierr);
}
ierr = TSSetIFunction(ts,NULL,IFunction_LaxWendroff,&appctx);CHKERRQ(ierr);
} else {
if (!rank) {
ierr = PetscPrintf(PETSC_COMM_SELF,"... Use Lax-LaxFriedrichs finite difference\n");CHKERRQ(ierr);
}
ierr = TSSetIFunction(ts,NULL,IFunction_LaxFriedrichs,&appctx);CHKERRQ(ierr);
}
/* Customize timestepping solver */
ierr = DMDAGetInfo(da,PETSC_IGNORE,&M,0,0,0,0,0,0,0,0,0,0,0);CHKERRQ(ierr);
dt = 1.0/(PetscAbsReal(appctx.a)*M);
ierr = TSSetTimeStep(ts,dt);CHKERRQ(ierr);
ierr = TSSetMaxSteps(ts,100);CHKERRQ(ierr);
ierr = TSSetMaxTime(ts,100.0);CHKERRQ(ierr);
ierr = TSSetExactFinalTime(ts,TS_EXACTFINALTIME_STEPOVER);CHKERRQ(ierr);
ierr = TSSetType(ts,TSBEULER);CHKERRQ(ierr);
ierr = TSSetFromOptions(ts);CHKERRQ(ierr);
/* Evaluate initial conditions */
ierr = InitialConditions(ts,U,&appctx);CHKERRQ(ierr);
/* For testing accuracy of TS with already known solution, e.g., '-ts_monitor_lg_error' */
ierr = TSSetSolutionFunction(ts,(PetscErrorCode (*)(TS,PetscReal,Vec,void*))Solution,&appctx);CHKERRQ(ierr);
/* Run the timestepping solver */
ierr = TSSolve(ts,U);CHKERRQ(ierr);
/* Free work space */
ierr = TSDestroy(&ts);CHKERRQ(ierr);
ierr = VecDestroy(&U);CHKERRQ(ierr);
ierr = DMDestroy(&da);CHKERRQ(ierr);
ierr = PetscFinalize();
return ierr;
}
