1 static char help[] = "Example program demonstrating projection between particle and finite element spaces\n\n"; 2 3 #include "petscdmplex.h" 4 #include "petscds.h" 5 #include "petscdmswarm.h" 6 #include "petscksp.h" 7 8 int main(int argc, char **argv) { 9 DM dm, sw; 10 PetscFE fe; 11 KSP ksp; 12 PC pc; 13 Mat M_p, PM_p = NULL; 14 Vec f, rho, rhs; 15 PetscInt dim, Nc = 1, timestep = 0, i, faces[3]; 16 PetscInt Np = 10, p, field = 0, zero = 0, bs; 17 PetscReal time = 0.0, norm, energy_0, energy_1; 18 PetscReal lo[3], hi[3], h[3]; 19 PetscBool removePoints = PETSC_TRUE; 20 PetscReal *wq, *coords; 21 PetscDataType dtype; 22 PetscBool is_bjac; 23 24 PetscFunctionBeginUser; 25 PetscCall(PetscInitialize(&argc, &argv, NULL, help)); 26 /* Create a mesh */ 27 PetscCall(DMCreate(PETSC_COMM_WORLD, &dm)); 28 PetscCall(DMSetType(dm, DMPLEX)); 29 PetscCall(DMSetFromOptions(dm)); 30 PetscCall(DMViewFromOptions(dm, NULL, "-dm_view")); 31 32 PetscCall(DMGetDimension(dm, &dim)); 33 i = dim; 34 PetscCall(PetscOptionsGetIntArray(NULL, NULL, "-dm_plex_box_faces", faces, &i, NULL)); 35 PetscCall(PetscOptionsGetInt(NULL, NULL, "-np", &Np, NULL)); 36 PetscCall(DMGetBoundingBox(dm, lo, hi)); 37 for (i = 0; i < dim; i++) { 38 h[i] = (hi[i] - lo[i]) / faces[i]; 39 PetscCall(PetscPrintf(PETSC_COMM_SELF, " lo = %g hi = %g n = %" PetscInt_FMT " h = %g\n", (double)lo[i], (double)hi[i], faces[i], (double)h[i])); 40 } 41 42 PetscCall(PetscFECreateDefault(PETSC_COMM_SELF, dim, Nc, PETSC_FALSE, "", PETSC_DECIDE, &fe)); 43 PetscCall(PetscFESetFromOptions(fe)); 44 PetscCall(PetscObjectSetName((PetscObject)fe, "fe")); 45 PetscCall(DMSetField(dm, field, NULL, (PetscObject)fe)); 46 PetscCall(DMCreateDS(dm)); 47 PetscCall(PetscFEDestroy(&fe)); 48 /* Create particle swarm */ 49 PetscCall(DMCreate(PETSC_COMM_SELF, &sw)); 50 PetscCall(DMSetType(sw, DMSWARM)); 51 PetscCall(DMSetDimension(sw, dim)); 52 PetscCall(DMSwarmSetType(sw, DMSWARM_PIC)); 53 PetscCall(DMSwarmSetCellDM(sw, dm)); 54 PetscCall(DMSwarmRegisterPetscDatatypeField(sw, "w_q", Nc, PETSC_SCALAR)); 55 PetscCall(DMSwarmFinalizeFieldRegister(sw)); 56 PetscCall(DMSwarmSetLocalSizes(sw, Np, zero)); 57 PetscCall(DMSetFromOptions(sw)); 58 PetscCall(DMSwarmGetField(sw, "w_q", &bs, &dtype, (void **)&wq)); 59 PetscCall(DMSwarmGetField(sw, "DMSwarmPIC_coor", &bs, &dtype, (void **)&coords)); 60 for (p = 0, energy_0 = 0; p < Np; p++) { 61 coords[p * 2 + 0] = -PetscCosReal((PetscReal)(p + 1) / (PetscReal)(Np + 1) * PETSC_PI); 62 coords[p * 2 + 1] = PetscSinReal((PetscReal)(p + 1) / (PetscReal)(Np + 1) * PETSC_PI); 63 wq[p] = 1.0; 64 energy_0 += wq[p] * (PetscSqr(coords[p * 2 + 0]) + PetscSqr(coords[p * 2 + 1])); 65 } 66 PetscCall(DMSwarmRestoreField(sw, "DMSwarmPIC_coor", &bs, &dtype, (void **)&coords)); 67 PetscCall(DMSwarmRestoreField(sw, "w_q", &bs, &dtype, (void **)&wq)); 68 PetscCall(DMSwarmMigrate(sw, removePoints)); 69 PetscCall(PetscObjectSetName((PetscObject)sw, "Particle Grid")); 70 PetscCall(DMViewFromOptions(sw, NULL, "-swarm_view")); 71 72 /* Project particles to field */ 73 /* This gives M f = \int_\Omega \phi f, which looks like a rhs for a PDE */ 74 PetscCall(DMCreateMassMatrix(sw, dm, &M_p)); 75 PetscCall(DMCreateGlobalVector(dm, &rho)); 76 PetscCall(PetscObjectSetName((PetscObject)rho, "rho")); 77 78 PetscCall(DMSwarmCreateGlobalVectorFromField(sw, "w_q", &f)); 79 PetscCall(PetscObjectSetName((PetscObject)f, "weights")); 80 PetscCall(MatMultTranspose(M_p, f, rho)); 81 82 /* Visualize mesh field */ 83 PetscCall(DMSetOutputSequenceNumber(dm, timestep, time)); 84 PetscCall(VecViewFromOptions(rho, NULL, "-rho_view")); 85 86 /* Project field to particles */ 87 /* This gives f_p = M_p^+ M f */ 88 PetscCall(DMCreateGlobalVector(dm, &rhs)); 89 PetscCall(VecCopy(rho, rhs)); /* Identity: M^1 M rho */ 90 91 PetscCall(KSPCreate(PETSC_COMM_WORLD, &ksp)); 92 PetscCall(KSPSetOptionsPrefix(ksp, "ftop_")); 93 PetscCall(KSPSetFromOptions(ksp)); 94 PetscCall(KSPGetPC(ksp, &pc)); 95 PetscCall(PetscObjectTypeCompare((PetscObject)pc, PCBJACOBI, &is_bjac)); 96 if (is_bjac) { 97 PetscCall(DMSwarmCreateMassMatrixSquare(sw, dm, &PM_p)); 98 PetscCall(KSPSetOperators(ksp, M_p, PM_p)); 99 } else { 100 PetscCall(KSPSetOperators(ksp, M_p, M_p)); 101 } 102 PetscCall(KSPSolveTranspose(ksp, rhs, f)); 103 PetscCall(KSPDestroy(&ksp)); 104 PetscCall(VecDestroy(&rhs)); 105 106 /* Visualize particle field */ 107 PetscCall(DMSetOutputSequenceNumber(sw, timestep, time)); 108 PetscCall(VecViewFromOptions(f, NULL, "-weights_view")); 109 PetscCall(VecNorm(f, NORM_1, &norm)); 110 PetscCall(DMSwarmDestroyGlobalVectorFromField(sw, "w_q", &f)); 111 112 /* compute energy */ 113 PetscCall(DMSwarmGetField(sw, "w_q", &bs, &dtype, (void **)&wq)); 114 PetscCall(DMSwarmGetField(sw, "DMSwarmPIC_coor", &bs, &dtype, (void **)&coords)); 115 for (p = 0, energy_1 = 0; p < Np; p++) energy_1 += wq[p] * (PetscSqr(coords[p * 2 + 0]) + PetscSqr(coords[p * 2 + 1])); 116 PetscCall(DMSwarmRestoreField(sw, "DMSwarmPIC_coor", &bs, &dtype, (void **)&coords)); 117 PetscCall(DMSwarmRestoreField(sw, "w_q", &bs, &dtype, (void **)&wq)); 118 PetscCall(PetscPrintf(PETSC_COMM_SELF, "Total number = %20.12e. energy = %20.12e error = %20.12e\n", (double)norm, (double)energy_0, (double)((energy_1 - energy_0) / energy_0))); 119 /* Cleanup */ 120 PetscCall(MatDestroy(&M_p)); 121 PetscCall(MatDestroy(&PM_p)); 122 PetscCall(VecDestroy(&rho)); 123 PetscCall(DMDestroy(&sw)); 124 PetscCall(DMDestroy(&dm)); 125 PetscCall(PetscFinalize()); 126 return 0; 127 } 128 129 /*TEST 130 131 build: 132 requires: !complex 133 134 test: 135 suffix: 0 136 requires: double triangle 137 args: -dm_plex_simplex 0 -dm_plex_box_faces 4,2 -np 50 -dm_plex_box_lower -2.0,0.0 -dm_plex_box_upper 2.0,2.0 -petscspace_degree 2 -ftop_ksp_type lsqr -ftop_pc_type none -dm_view -swarm_view -ftop_ksp_rtol 1.e-14 138 filter: grep -v DM_ | grep -v atomic 139 140 test: 141 suffix: bjacobi 142 requires: double triangle 143 args: -dm_plex_simplex 0 -dm_plex_box_faces 4,2 -np 50 -dm_plex_box_lower -2.0,0.0 -dm_plex_box_upper 2.0,2.0 -petscspace_degree 2 -dm_plex_hash_location -ftop_ksp_type lsqr -ftop_pc_type bjacobi -ftop_sub_pc_type lu -ftop_sub_pc_factor_shift_type nonzero -dm_view -swarm_view -ftop_ksp_rtol 1.e-14 144 filter: grep -v DM_ | grep -v atomic 145 146 TEST*/ 147