Actual source code: ex30.c
petsc-3.7.7 2017-09-25
1: static char help[] = "Tests DMSLICED operations\n\n";
3: #include <petscdmsliced.h>
7: int main(int argc,char *argv[])
8: {
9: char mat_type[256] = "aij"; /* default matrix type */
11: MPI_Comm comm;
12: PetscMPIInt rank,size;
13: DM slice;
14: PetscInt i,bs=1,N=5,n,m,rstart,ghosts[2],*d_nnz,*o_nnz,dfill[4]={1,0,0,1},ofill[4]={1,1,1,1};
15: PetscReal alpha =1,K=1,rho0=1,u0=0,sigma=0.2;
16: PetscBool useblock=PETSC_TRUE;
17: PetscScalar *xx;
18: Mat A;
19: Vec x,b,lf;
21: PetscInitialize(&argc,&argv,0,help);
22: comm = PETSC_COMM_WORLD;
23: MPI_Comm_size(comm,&size);
24: MPI_Comm_rank(comm,&rank);
26: PetscOptionsBegin(comm,0,"Options for DMSliced test",0);
27: {
28: PetscOptionsInt("-n","Global number of nodes","",N,&N,NULL);
29: PetscOptionsInt("-bs","Block size (1 or 2)","",bs,&bs,NULL);
30: if (bs != 1) {
31: if (bs != 2) SETERRQ(PETSC_COMM_WORLD,1,"Block size must be 1 or 2");
32: PetscOptionsReal("-alpha","Inverse time step for wave operator","",alpha,&alpha,NULL);
33: PetscOptionsReal("-K","Bulk modulus of compressibility","",K,&K,NULL);
34: PetscOptionsReal("-rho0","Reference density","",rho0,&rho0,NULL);
35: PetscOptionsReal("-u0","Reference velocity","",u0,&u0,NULL);
36: PetscOptionsReal("-sigma","Width of Gaussian density perturbation","",sigma,&sigma,NULL);
37: PetscOptionsBool("-block","Use block matrix assembly","",useblock,&useblock,NULL);
38: }
39: PetscOptionsString("-sliced_mat_type","Matrix type to use (aij or baij)","",mat_type,mat_type,sizeof(mat_type),NULL);
40: }
41: PetscOptionsEnd();
43: /* Split ownership, set up periodic grid in 1D */
44: n = PETSC_DECIDE;
45: PetscSplitOwnership(comm,&n,&N);
46: rstart = 0;
47: MPI_Scan(&n,&rstart,1,MPIU_INT,MPI_SUM,comm);
48: rstart -= n;
49: ghosts[0] = (N+rstart-1)%N;
50: ghosts[1] = (rstart+n)%N;
52: PetscMalloc2(n,&d_nnz,n,&o_nnz);
53: for (i=0; i<n; i++) {
54: if (size > 1 && (i==0 || i==n-1)) {
55: d_nnz[i] = 2;
56: o_nnz[i] = 1;
57: } else {
58: d_nnz[i] = 3;
59: o_nnz[i] = 0;
60: }
61: }
62: DMSlicedCreate(comm,bs,n,2,ghosts,d_nnz,o_nnz,&slice); /* Currently does not copy X_nnz so we can't free them until after DMSlicedGetMatrix */
64: if (!useblock) {DMSlicedSetBlockFills(slice,dfill,ofill);} /* Irrelevant for baij formats */
65: DMSetMatType(slice,mat_type);
66: DMCreateMatrix(slice,&A);
67: PetscFree2(d_nnz,o_nnz);
68: MatSetOption(A,MAT_NEW_NONZERO_ALLOCATION_ERR,PETSC_TRUE);
70: DMCreateGlobalVector(slice,&x);
71: VecDuplicate(x,&b);
73: VecGhostGetLocalForm(x,&lf);
74: VecGetSize(lf,&m);
75: if (m != (n+2)*bs) SETERRQ2(PETSC_COMM_SELF,1,"size of local form %D, expected %D",m,(n+2)*bs);
76: VecGetArray(lf,&xx);
77: for (i=0; i<n; i++) {
78: PetscInt row[2],col[9],im,ip;
79: PetscScalar v[12];
80: const PetscReal xref = 2.0*(rstart+i)/N - 1; /* [-1,1] */
81: const PetscReal h = 1.0/N; /* grid spacing */
82: im = (i==0) ? n : i-1;
83: ip = (i==n-1) ? n+1 : i+1;
84: switch (bs) {
85: case 1: /* Laplacian with periodic boundaries */
86: col[0] = im; col[1] = i; col[2] = ip;
87: v[0] = -h; v[1] = 2*h; v[2] = -h;
88: MatSetValuesLocal(A,1,&i,3,col,v,INSERT_VALUES);
89: xx[i] = PetscSinReal(xref*PETSC_PI);
90: break;
91: case 2: /* Linear acoustic wave operator in variables [rho, u], central differences, periodic, timestep 1/alpha */
92: v[0] = -0.5*u0; v[1] = -0.5*K; v[2] = alpha; v[3] = 0; v[4] = 0.5*u0; v[5] = 0.5*K;
93: v[6] = -0.5/rho0; v[7] = -0.5*u0; v[8] = 0; v[9] = alpha; v[10] = 0.5/rho0; v[11] = 0.5*u0;
94: if (useblock) {
95: row[0] = i; col[0] = im; col[1] = i; col[2] = ip;
96: MatSetValuesBlockedLocal(A,1,row,3,col,v,INSERT_VALUES);
97: } else {
98: row[0] = 2*i; row[1] = 2*i+1;
99: col[0] = 2*im; col[1] = 2*im+1; col[2] = 2*i; col[3] = 2*ip; col[4] = 2*ip+1;
100: v[3] = v[4]; v[4] = v[5]; /* pack values in first row */
101: MatSetValuesLocal(A,1,row,5,col,v,INSERT_VALUES);
102: col[2] = 2*i+1;
103: v[8] = v[9]; v[9] = v[10]; v[10] = v[11]; /* pack values in second row */
104: MatSetValuesLocal(A,1,row+1,5,col,v+6,INSERT_VALUES);
105: }
106: /* Set current state (gaussian density perturbation) */
107: xx[2*i] = 0.2*PetscExpReal(-PetscSqr(xref)/(2*PetscSqr(sigma)));
108: xx[2*i+1] = 0;
109: break;
110: default: SETERRQ1(PETSC_COMM_SELF,1,"not implemented for block size %D",bs);
111: }
112: }
113: VecRestoreArray(lf,&xx);
114: VecGhostRestoreLocalForm(x,&lf);
115: MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
116: MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);
118: MatMult(A,x,b);
119: MatView(A,PETSC_VIEWER_STDOUT_WORLD);
120: VecView(x,PETSC_VIEWER_STDOUT_WORLD);
121: VecView(b,PETSC_VIEWER_STDOUT_WORLD);
123: /* Update the ghosted values, view the result on rank 0. */
124: VecGhostUpdateBegin(b,INSERT_VALUES,SCATTER_FORWARD);
125: VecGhostUpdateEnd(b,INSERT_VALUES,SCATTER_FORWARD);
126: if (!rank) {
127: VecGhostGetLocalForm(b,&lf);
128: PetscViewerASCIIPrintf(PETSC_VIEWER_STDOUT_SELF,"Local form of b on rank 0, last two nodes are ghost nodes\n");
129: VecView(lf,PETSC_VIEWER_STDOUT_SELF);
130: VecGhostRestoreLocalForm(b,&lf);
131: }
133: DMDestroy(&slice);
134: VecDestroy(&x);
135: VecDestroy(&b);
136: MatDestroy(&A);
137: PetscFinalize();
138: return 0;
139: }