/* Fortran interface to C routine ARKPcg and it's associated
"set" routines; see farkode.h for further details */
void FARK_PCG(int *pretype, int *maxl, realtype *delt, int *ier) {
*ier = ARKPcg(ARK_arkodemem, *pretype, *maxl);
if (*ier != ARKSPILS_SUCCESS) return;
*ier = ARKSpilsSetEpsLin(ARK_arkodemem, *delt);
if (*ier != ARKSPILS_SUCCESS) return;
ARK_ls = ARK_LS_PCG;
return;
}
/* Main Program */
int main() {
/* general problem parameters */
realtype T0 = RCONST(0.0); /* initial time */
realtype Tf = RCONST(1.0); /* final time */
realtype rtol = 1.e-3; /* relative tolerance */
realtype atol = 1.e-10; /* absolute tolerance */
realtype hscale = 1.0; /* time step change factor on resizes */
UserData udata = NULL;
realtype *data;
long int N = 21; /* initial spatial mesh size */
realtype refine = 3.e-3; /* adaptivity refinement tolerance */
realtype k = 0.5; /* heat conductivity */
long int i, nni, nni_cur=0, nni_tot=0, nli, nli_tot=0;
int iout=0;
/* general problem variables */
int flag; /* reusable error-checking flag */
N_Vector y = NULL; /* empty vector for storing solution */
N_Vector y2 = NULL; /* empty vector for storing solution */
N_Vector yt = NULL; /* empty vector for swapping */
void *arkode_mem = NULL; /* empty ARKode memory structure */
FILE *XFID, *UFID;
realtype t, olddt, newdt;
realtype *xnew = NULL;
long int Nnew;
/* allocate and fill initial udata structure */
udata = (UserData) malloc(sizeof(*udata));
udata->N = N;
udata->k = k;
udata->refine_tol = refine;
udata->x = malloc(N * sizeof(realtype));
for (i=0; i<N; i++) udata->x[i] = 1.0*i/(N-1);
/* Initial problem output */
printf("\n1D adaptive Heat PDE test problem:\n");
printf(" diffusion coefficient: k = %g\n", udata->k);
printf(" initial N = %li\n", udata->N);
/* Initialize data structures */
y = N_VNew_Serial(N); /* Create initial serial vector for solution */
if (check_flag((void *) y, "N_VNew_Serial", 0)) return 1;
N_VConst(0.0, y); /* Set initial conditions */
/* output mesh to disk */
XFID=fopen("heat_mesh.txt","w");
/* output initial mesh to disk */
for (i=0; i<udata->N; i++) fprintf(XFID," %.16e", udata->x[i]);
fprintf(XFID,"\n");
/* Open output stream for results, access data array */
UFID=fopen("heat1D.txt","w");
/* output initial condition to disk */
data = N_VGetArrayPointer(y);
for (i=0; i<udata->N; i++) fprintf(UFID," %.16e", data[i]);
fprintf(UFID,"\n");
/* Create the solver memory */
arkode_mem = ARKodeCreate();
if (check_flag((void *) arkode_mem, "ARKodeCreate", 0)) return 1;
/* Initialize the integrator memory */
flag = ARKodeInit(arkode_mem, NULL, f, T0, y);
if (check_flag(&flag, "ARKodeInit", 1)) return 1;
/* Set routines */
flag = ARKodeSetUserData(arkode_mem, (void *) udata); /* Pass udata to user functions */
if (check_flag(&flag, "ARKodeSetUserData", 1)) return 1;
flag = ARKodeSetMaxNumSteps(arkode_mem, 10000); /* Increase max num steps */
if (check_flag(&flag, "ARKodeSetMaxNumSteps", 1)) return 1;
flag = ARKodeSStolerances(arkode_mem, rtol, atol); /* Specify tolerances */
if (check_flag(&flag, "ARKodeSStolerances", 1)) return 1;
flag = ARKodeSetAdaptivityMethod(arkode_mem, 2, 1, 0, NULL); /* Set adaptivity method */
if (check_flag(&flag, "ARKodeSetAdaptivityMethod", 1)) return 1;
flag = ARKodeSetPredictorMethod(arkode_mem, 0); /* Set predictor method */
if (check_flag(&flag, "ARKodeSetPredictorMethod", 1)) return 1;
/* Linear solver specification */
flag = ARKPcg(arkode_mem, 0, N);
if (check_flag(&flag, "ARKPcg", 1)) return 1;
flag = ARKSpilsSetJacTimesVecFn(arkode_mem, Jac);
if (check_flag(&flag, "ARKSpilsSetJacTimesVecFn", 1)) return 1;
/* Main time-stepping loop: calls ARKode to perform the integration, then
prints results. Stops when the final time has been reached */
t = T0;
olddt = 0.0;
newdt = 0.0;
printf(" iout dt_old dt_new ||u||_rms N NNI NLI\n");
printf(" ----------------------------------------------------------------------------------------\n");
printf(" %4i %19.15e %19.15e %19.15e %li %2i %3i\n",
iout, olddt, newdt, sqrt(N_VDotProd(y,y)/udata->N), udata->N, 0, 0);
while (t < Tf) {
/* "set" routines */
flag = ARKodeSetStopTime(arkode_mem, Tf);
if (check_flag(&flag, "ARKodeSetStopTime", 1)) return 1;
flag = ARKodeSetInitStep(arkode_mem, newdt);
if (check_flag(&flag, "ARKodeSetInitStep", 1)) return 1;
/* call integrator */
flag = ARKode(arkode_mem, Tf, y, &t, ARK_ONE_STEP);
if (check_flag(&flag, "ARKode", 1)) return 1;
/* "get" routines */
flag = ARKodeGetLastStep(arkode_mem, &olddt);
if (check_flag(&flag, "ARKodeGetLastStep", 1)) return 1;
flag = ARKodeGetCurrentStep(arkode_mem, &newdt);
if (check_flag(&flag, "ARKodeGetCurrentStep", 1)) return 1;
flag = ARKodeGetNumNonlinSolvIters(arkode_mem, &nni);
if (check_flag(&flag, "ARKodeGetNumNonlinSolvIters", 1)) return 1;
flag = ARKSpilsGetNumLinIters(arkode_mem, &nli);
if (check_flag(&flag, "ARKSpilsGetNumLinIters", 1)) return 1;
/* print current solution stats */
iout++;
printf(" %4i %19.15e %19.15e %19.15e %li %2li %3li\n",
iout, olddt, newdt, sqrt(N_VDotProd(y,y)/udata->N), udata->N, nni-nni_cur, nli);
nni_cur = nni;
nni_tot = nni;
nli_tot += nli;
/* output results and current mesh to disk */
data = N_VGetArrayPointer(y);
for (i=0; i<udata->N; i++) fprintf(UFID," %.16e", data[i]);
fprintf(UFID,"\n");
for (i=0; i<udata->N; i++) fprintf(XFID," %.16e", udata->x[i]);
fprintf(XFID,"\n");
/* adapt the spatial mesh */
xnew = adapt_mesh(y, &Nnew, udata);
if (check_flag(xnew, "ark_adapt", 0)) return 1;
/* create N_Vector of new length */
y2 = N_VNew_Serial(Nnew);
if (check_flag((void *) y2, "N_VNew_Serial", 0)) return 1;
/* project solution onto new mesh */
flag = project(udata->N, udata->x, y, Nnew, xnew, y2);
if (check_flag(&flag, "project", 1)) return 1;
/* delete old vector, old mesh */
N_VDestroy_Serial(y);
free(udata->x);
/* swap x and xnew so that new mesh is stored in udata structure */
udata->x = xnew;
xnew = NULL;
udata->N = Nnew; /* store size of new mesh */
/* swap y and y2 so that y holds new solution */
yt = y;
y = y2;
y2 = yt;
/* call ARKodeResize to notify integrator of change in mesh */
flag = ARKodeResize(arkode_mem, y, hscale, t, NULL, NULL);
if (check_flag(&flag, "ARKodeResize", 1)) return 1;
/* destroy and re-allocate linear solver memory */
flag = ARKPcg(arkode_mem, 0, udata->N);
if (check_flag(&flag, "ARKPcg", 1)) return 1;
flag = ARKSpilsSetJacTimesVecFn(arkode_mem, Jac);
if (check_flag(&flag, "ARKSpilsSetJacTimesVecFn", 1)) return 1;
}
printf(" ----------------------------------------------------------------------------------------\n");
/* Free integrator memory */
ARKodeFree(&arkode_mem);
/* print some final statistics */
printf(" Final solver statistics:\n");
printf(" Total number of time steps = %i\n", iout);
printf(" Total nonlinear iterations = %li\n", nni_tot);
printf(" Total linear iterations = %li\n\n", nli_tot);
/* Clean up and return with successful completion */
fclose(UFID);
fclose(XFID);
N_VDestroy_Serial(y); /* Free vectors */
free(udata->x); /* Free user data */
free(udata);
return 0;
}
