Actual source code: radau5.c

  1: /*
  2:     Provides a PETSc interface to RADAU5 solver.

  4: */
  5: #include <petsc/private/tsimpl.h>

  7: typedef struct {
  8:   Vec work, workf;
  9: } TS_Radau5;

 11: static void FVPOL(int *N, double *X, double *Y, double *F, double *RPAR, void *IPAR)
 12: {
 13:   TS             ts    = (TS)IPAR;
 14:   TS_Radau5     *cvode = (TS_Radau5 *)ts->data;
 15:   DM             dm;
 16:   DMTS           tsdm;
 17:   TSIFunctionFn *ifunction;

 19:   PetscCallAbort(PETSC_COMM_SELF, VecPlaceArray(cvode->work, Y));
 20:   PetscCallAbort(PETSC_COMM_SELF, VecPlaceArray(cvode->workf, F));

 22:   /* Now compute the right-hand side function, via IFunction unless only the more efficient RHSFunction is set */
 23:   PetscCallAbort(PETSC_COMM_SELF, TSGetDM(ts, &dm));
 24:   PetscCallAbort(PETSC_COMM_SELF, DMGetDMTS(dm, &tsdm));
 25:   PetscCallAbort(PETSC_COMM_SELF, DMTSGetIFunction(dm, &ifunction, NULL));
 26:   if (!ifunction) {
 27:     PetscCallAbort(PETSC_COMM_SELF, TSComputeRHSFunction(ts, *X, cvode->work, cvode->workf));
 28:   } else { /* If rhsfunction is also set, this computes both parts and scale them to the right-hand side */
 29:     Vec yydot;

 31:     PetscCallAbort(PETSC_COMM_SELF, VecDuplicate(cvode->work, &yydot));
 32:     PetscCallAbort(PETSC_COMM_SELF, VecZeroEntries(yydot));
 33:     PetscCallAbort(PETSC_COMM_SELF, TSComputeIFunction(ts, *X, cvode->work, yydot, cvode->workf, PETSC_FALSE));
 34:     PetscCallAbort(PETSC_COMM_SELF, VecScale(cvode->workf, -1.));
 35:     PetscCallAbort(PETSC_COMM_SELF, VecDestroy(&yydot));
 36:   }

 38:   PetscCallAbort(PETSC_COMM_SELF, VecResetArray(cvode->work));
 39:   PetscCallAbort(PETSC_COMM_SELF, VecResetArray(cvode->workf));
 40: }

 42: static void JVPOL(PetscInt *N, PetscScalar *X, PetscScalar *Y, PetscScalar *DFY, int *LDFY, PetscScalar *RPAR, void *IPAR)
 43: {
 44:   TS         ts    = (TS)IPAR;
 45:   TS_Radau5 *cvode = (TS_Radau5 *)ts->data;
 46:   Vec        yydot;
 47:   Mat        mat;
 48:   PetscInt   n;

 50:   PetscCallAbort(PETSC_COMM_SELF, VecPlaceArray(cvode->work, Y));
 51:   PetscCallAbort(PETSC_COMM_SELF, VecDuplicate(cvode->work, &yydot));
 52:   PetscCallAbort(PETSC_COMM_SELF, VecGetSize(yydot, &n));
 53:   PetscCallAbort(PETSC_COMM_SELF, MatCreateSeqDense(PETSC_COMM_SELF, n, n, DFY, &mat));
 54:   PetscCallAbort(PETSC_COMM_SELF, VecZeroEntries(yydot));
 55:   PetscCallAbort(PETSC_COMM_SELF, TSComputeIJacobian(ts, *X, cvode->work, yydot, 0, mat, mat, PETSC_FALSE));
 56:   PetscCallAbort(PETSC_COMM_SELF, MatScale(mat, -1.0));
 57:   PetscCallAbort(PETSC_COMM_SELF, MatDestroy(&mat));
 58:   PetscCallAbort(PETSC_COMM_SELF, VecDestroy(&yydot));
 59:   PetscCallAbort(PETSC_COMM_SELF, VecResetArray(cvode->work));
 60: }

 62: static void SOLOUT(int *NR, double *XOLD, double *X, double *Y, double *CONT, double *LRC, int *N, double *RPAR, void *IPAR, int *IRTRN)
 63: {
 64:   TS         ts    = (TS)IPAR;
 65:   TS_Radau5 *cvode = (TS_Radau5 *)ts->data;

 67:   PetscCallAbort(PETSC_COMM_SELF, VecPlaceArray(cvode->work, Y));
 68:   ts->time_step = *X - *XOLD;
 69:   PetscCallAbort(PETSC_COMM_SELF, TSMonitor(ts, *NR - 1, *X, cvode->work));
 70:   PetscCallAbort(PETSC_COMM_SELF, VecResetArray(cvode->work));
 71: }

 73: static void radau5_(int *, void *, double *, double *, double *, double *, double *, double *, int *, void *, int *, int *, int *, void *, int *, int *, int *, void *, int *, double *, int *, int *, int *, double *, void *, int *);

 75: static PetscErrorCode TSSolve_Radau5(TS ts)
 76: {
 77:   TS_Radau5   *cvode = (TS_Radau5 *)ts->data;
 78:   PetscScalar *Y, *WORK, X, XEND, RTOL, ATOL, H, RPAR;
 79:   PetscInt     ND, *IWORK, LWORK, LIWORK, MUJAC, MLMAS, MUMAS, IDID, ITOL;
 80:   int          IJAC, MLJAC, IMAS, IOUT;

 82:   PetscFunctionBegin;
 83:   PetscCall(VecGetArray(ts->vec_sol, &Y));
 84:   PetscCall(VecGetSize(ts->vec_sol, &ND));
 85:   PetscCall(VecCreateSeqWithArray(PETSC_COMM_SELF, 1, ND, NULL, &cvode->work));
 86:   PetscCall(VecCreateSeqWithArray(PETSC_COMM_SELF, 1, ND, NULL, &cvode->workf));

 88:   LWORK  = 4 * ND * ND + 12 * ND + 20;
 89:   LIWORK = 3 * ND + 20;

 91:   PetscCall(PetscCalloc2(LWORK, &WORK, LIWORK, &IWORK));

 93:   /* C --- PARAMETER IN THE DIFFERENTIAL EQUATION */
 94:   RPAR = 1.0e-6;
 95:   /* C --- COMPUTE THE JACOBIAN ANALYTICALLY */
 96:   IJAC = 1;
 97:   /* C --- JACOBIAN IS A FULL MATRIX */
 98:   MLJAC = ND;
 99:   /* C --- DIFFERENTIAL EQUATION IS IN EXPLICIT FORM*/
100:   IMAS = 0;
101:   /* C --- OUTPUT ROUTINE IS USED DURING INTEGRATION*/
102:   IOUT = 1;
103:   /* C --- INITIAL VALUES*/
104:   X = ts->ptime;
105:   /* C --- ENDPOINT OF INTEGRATION */
106:   XEND = ts->max_time;
107:   /* C --- REQUIRED TOLERANCE */
108:   RTOL = ts->rtol;
109:   ATOL = ts->atol;
110:   ITOL = 0;
111:   /* C --- INITIAL STEP SIZE */
112:   H = ts->time_step;

114:   /* output MUJAC MLMAS IDID; currently all ignored */

116:   radau5_(&ND, FVPOL, &X, Y, &XEND, &H, &RTOL, &ATOL, &ITOL, JVPOL, &IJAC, &MLJAC, &MUJAC, FVPOL, &IMAS, &MLMAS, &MUMAS, SOLOUT, &IOUT, WORK, &LWORK, IWORK, &LIWORK, &RPAR, (void *)ts, &IDID);

118:   PetscCall(PetscFree2(WORK, IWORK));
119:   PetscFunctionReturn(PETSC_SUCCESS);
120: }

122: static PetscErrorCode TSDestroy_Radau5(TS ts)
123: {
124:   TS_Radau5 *cvode = (TS_Radau5 *)ts->data;

126:   PetscFunctionBegin;
127:   PetscCall(VecDestroy(&cvode->work));
128:   PetscCall(VecDestroy(&cvode->workf));
129:   PetscCall(PetscFree(ts->data));
130:   PetscFunctionReturn(PETSC_SUCCESS);
131: }

133: /*MC
134:       TSRADAU5 - ODE solver using the external RADAU5 package, requires ./configure --download-radau5

136:     Level: beginner

138:     Notes:
139:     This uses its own nonlinear solver and dense matrix direct solver so PETSc `SNES` and `KSP` options do not apply.

141:     Uses its own time-step adaptivity (but uses the TS rtol and atol, and initial timestep)

143:     Uses its own memory for the dense matrix storage and factorization

145:     Can only handle ODEs of the form \cdot{u} = -F(t,u) + G(t,u)

147: .seealso: [](ch_ts), `TSCreate()`, `TS`, `TSSetType()`, `TSType`
148: M*/
149: PETSC_EXTERN PetscErrorCode TSCreate_Radau5(TS ts)
150: {
151:   TS_Radau5 *cvode;

153:   PetscFunctionBegin;
154:   ts->ops->destroy       = TSDestroy_Radau5;
155:   ts->ops->solve         = TSSolve_Radau5;
156:   ts->default_adapt_type = TSADAPTNONE;

158:   PetscCall(PetscNew(&cvode));
159:   ts->data = (void *)cvode;
160:   PetscFunctionReturn(PETSC_SUCCESS);
161: }