Actual source code: ex5.c
1: static char help[] = "Test DMStag ghosted boundaries in 1d\n\n";
2: /* This solves a very contrived problem - the "pressure" terms are set to a constant function
3: and the "velocity" terms are just the sum of neighboring values of these, hence twice the
4: constant */
5: #include <petscdm.h>
6: #include <petscksp.h>
7: #include <petscdmstag.h>
9: #define LEFT DMSTAG_LEFT
10: #define RIGHT DMSTAG_RIGHT
11: #define ELEMENT DMSTAG_ELEMENT
13: #define PRESSURE_CONST 2.0
15: PetscErrorCode ApplyOperator(Mat, Vec, Vec);
17: int main(int argc, char **argv)
18: {
19: DM dmSol;
20: Vec sol, solRef, solRefLocal, rhs, rhsLocal;
21: Mat A;
22: KSP ksp;
23: PC pc;
24: PetscInt start, n, e, nExtra;
25: PetscInt iu, ip;
26: PetscScalar **arrSol, **arrRHS;
29: PetscInitialize(&argc, &argv, (char *)0, help);
30: DMStagCreate1d(PETSC_COMM_WORLD, DM_BOUNDARY_GHOSTED, 3, 1, 1, DMSTAG_STENCIL_BOX, 1, NULL, &dmSol);
31: DMSetFromOptions(dmSol);
32: DMSetUp(dmSol);
34: /* Compute reference solution on the grid, using direct array access */
35: DMCreateGlobalVector(dmSol, &rhs);
36: DMCreateGlobalVector(dmSol, &solRef);
37: DMGetLocalVector(dmSol, &solRefLocal);
38: DMGetLocalVector(dmSol, &rhsLocal);
39: DMStagVecGetArray(dmSol, solRefLocal, &arrSol);
41: DMStagGetCorners(dmSol, &start, NULL, NULL, &n, NULL, NULL, &nExtra, NULL, NULL);
42: DMStagVecGetArray(dmSol, rhsLocal, &arrRHS);
44: /* Get the correct entries for each of our variables in local element-wise storage */
45: DMStagGetLocationSlot(dmSol, LEFT, 0, &iu);
46: DMStagGetLocationSlot(dmSol, ELEMENT, 0, &ip);
47: for (e = start; e < start + n + nExtra; ++e) {
48: {
49: arrSol[e][iu] = 2 * PRESSURE_CONST;
50: arrRHS[e][iu] = 0.0;
51: }
52: if (e < start + n) {
53: arrSol[e][ip] = PRESSURE_CONST;
54: arrRHS[e][ip] = PRESSURE_CONST;
55: }
56: }
57: DMStagVecRestoreArray(dmSol, rhsLocal, &arrRHS);
58: DMLocalToGlobalBegin(dmSol, rhsLocal, INSERT_VALUES, rhs);
59: DMLocalToGlobalEnd(dmSol, rhsLocal, INSERT_VALUES, rhs);
60: DMStagVecRestoreArray(dmSol, solRefLocal, &arrSol);
61: DMLocalToGlobalBegin(dmSol, solRefLocal, INSERT_VALUES, solRef);
62: DMLocalToGlobalEnd(dmSol, solRefLocal, INSERT_VALUES, solRef);
63: DMRestoreLocalVector(dmSol, &solRefLocal);
64: DMRestoreLocalVector(dmSol, &rhsLocal);
66: /* Matrix-free Operator */
67: DMSetMatType(dmSol, MATSHELL);
68: DMCreateMatrix(dmSol, &A);
69: MatShellSetOperation(A, MATOP_MULT, (void (*)(void))ApplyOperator);
71: /* Solve */
72: DMCreateGlobalVector(dmSol, &sol);
73: KSPCreate(PETSC_COMM_WORLD, &ksp);
74: KSPSetOperators(ksp, A, A);
75: KSPGetPC(ksp, &pc);
76: PCSetType(pc, PCNONE);
77: KSPSetFromOptions(ksp);
78: KSPSolve(ksp, rhs, sol);
80: /* Check Solution */
81: {
82: Vec diff;
83: PetscReal normsolRef, errAbs, errRel;
85: VecDuplicate(sol, &diff);
86: VecCopy(sol, diff);
87: VecAXPY(diff, -1.0, solRef);
88: VecNorm(diff, NORM_2, &errAbs);
89: VecNorm(solRef, NORM_2, &normsolRef);
90: errRel = errAbs / normsolRef;
91: if (errAbs > 1e14 || errRel > 1e14) {
92: PetscPrintf(PetscObjectComm((PetscObject)dmSol), "Error (abs): %g\nError (rel): %g\n", (double)errAbs, (double)errRel);
93: PetscPrintf(PetscObjectComm((PetscObject)dmSol), "Non-zero error. Probable failure.\n");
94: }
95: VecDestroy(&diff);
96: }
98: KSPDestroy(&ksp);
99: VecDestroy(&sol);
100: VecDestroy(&solRef);
101: VecDestroy(&rhs);
102: MatDestroy(&A);
103: DMDestroy(&dmSol);
104: PetscFinalize();
105: return 0;
106: }
108: PetscErrorCode ApplyOperator(Mat A, Vec in, Vec out)
109: {
110: DM dm;
111: Vec inLocal, outLocal;
112: PetscScalar **arrIn;
113: PetscScalar **arrOut;
114: PetscInt start, n, nExtra, ex, idxP, idxU, startGhost, nGhost;
115: DMBoundaryType boundaryType;
116: PetscBool isFirst, isLast;
119: MatGetDM(A, &dm);
120: DMStagGetBoundaryTypes(dm, &boundaryType, NULL, NULL);
122: DMGetLocalVector(dm, &inLocal);
123: DMGetLocalVector(dm, &outLocal);
124: DMGlobalToLocalBegin(dm, in, INSERT_VALUES, inLocal);
125: DMGlobalToLocalEnd(dm, in, INSERT_VALUES, inLocal);
126: DMStagGetCorners(dm, &start, NULL, NULL, &n, NULL, NULL, &nExtra, NULL, NULL);
127: DMStagGetGhostCorners(dm, &startGhost, NULL, NULL, &nGhost, NULL, NULL);
128: DMStagVecGetArrayRead(dm, inLocal, &arrIn);
129: DMStagVecGetArray(dm, outLocal, &arrOut);
130: DMStagGetLocationSlot(dm, LEFT, 0, &idxU);
131: DMStagGetLocationSlot(dm, ELEMENT, 0, &idxP);
132: DMStagGetIsFirstRank(dm, &isFirst, NULL, NULL);
133: DMStagGetIsLastRank(dm, &isLast, NULL, NULL);
135: /* Set "pressures" on ghost boundaries by copying neighboring values*/
136: if (isFirst) arrIn[-1][idxP] = arrIn[0][idxP];
137: if (isLast) arrIn[start + n][idxP] = arrIn[start + n - 1][idxP];
139: /* Apply operator on physical points */
140: for (ex = start; ex < start + n + nExtra; ++ex) {
141: if (ex < start + n) { /* Don't compute pressure outside domain */
142: arrOut[ex][idxP] = arrIn[ex][idxP];
143: }
144: arrOut[ex][idxU] = arrIn[ex][idxP] + arrIn[ex - 1][idxP] - arrIn[ex][idxU];
145: }
146: DMStagVecRestoreArrayRead(dm, inLocal, &arrIn);
147: DMStagVecRestoreArray(dm, outLocal, &arrOut);
148: DMLocalToGlobalBegin(dm, outLocal, INSERT_VALUES, out);
149: DMLocalToGlobalEnd(dm, outLocal, INSERT_VALUES, out);
150: DMRestoreLocalVector(dm, &inLocal);
151: DMRestoreLocalVector(dm, &outLocal);
152: return 0;
153: }
155: /*TEST
157: test:
158: suffix: 1
159: nsize: 1
161: test:
162: suffix: 2
163: nsize: 2
165: test:
166: suffix: 3
167: nsize: 3
168: args: -stag_grid_x 19
170: test:
171: suffix: 4
172: nsize: 5
173: args: -stag_grid_x 21 -stag_stencil_width 2
175: TEST*/