Actual source code: mmbdiag.c
1: #define PETSCMAT_DLL
3: /*
4: Support for the MPIBDIAG matrix-vector multiply
5: */
6: #include src/mat/impls/bdiag/mpi/mpibdiag.h
10: PetscErrorCode MatSetUpMultiply_MPIBDiag(Mat mat)
11: {
12: Mat_MPIBDiag *mbd = (Mat_MPIBDiag*)mat->data;
13: Mat_SeqBDiag *lmbd = (Mat_SeqBDiag*)mbd->A->data;
15: PetscInt N = mat->cmap.N,*indices,*garray,ec=0;
16: PetscInt bs = mat->rmap.bs,d,i,j,diag;
17: IS to,from;
18: Vec gvec;
21: /* We make an array as long as the number of columns */
22: /* mark those columns that are in mbd->A */
23: PetscMalloc((N+1)*sizeof(PetscInt),&indices);
24: PetscMemzero(indices,N*sizeof(PetscInt));
26: if (bs == 1) {
27: for (d=0; d<lmbd->nd; d++) {
28: diag = lmbd->diag[d];
29: if (diag > 0) { /* col = loc */
30: for (j=0; j<lmbd->bdlen[d]; j++) {
31: if (!indices[j]) ec++;
32: indices[j] = 1;
33: }
34: } else { /* col = loc-diag */
35: for (j=0; j<lmbd->bdlen[d]; j++) {
36: if (!indices[j-diag]) ec++;
37: indices[j-diag] = 1;
38: }
39: }
40: }
41: } else {
42: for (d=0; d<lmbd->nd; d++) {
43: diag = lmbd->diag[d];
44: if (diag > 0) { /* col = loc */
45: for (j=0; j<lmbd->bdlen[d]; j++) {
46: if (!indices[bs*j]) ec += bs;
47: for (i=0; i<bs; i++) indices[bs*j+i] = 1;
48: }
49: } else { /* col = loc-diag */
50: for (j=0; j<lmbd->bdlen[d]; j++) {
51: if (!indices[bs*(j-diag)]) ec += bs;
52: for (i=0; i<bs; i++) indices[bs*(j-diag)+i] = 1;
53: }
54: }
55: }
56: }
58: /* form array of columns we need */
59: PetscMalloc((ec+1)*sizeof(PetscInt),&garray);
60: ec = 0;
61: for (i=0; i<N; i++) {
62: if (indices[i]) garray[ec++] = i;
63: }
64: PetscFree(indices);
66: /* create local vector that is used to scatter into */
67: VecCreateSeq(PETSC_COMM_SELF,N,&mbd->lvec);
69: /* create temporary index set for building scatter-gather */
70: ISCreateGeneral(mat->comm,ec,garray,&from);
71: ISCreateGeneral(PETSC_COMM_SELF,ec,garray,&to);
72: PetscFree(garray);
74: /* create temporary global vector to generate scatter context */
75: /* this is inefficient, but otherwise we must do either
76: 1) save garray until the first actual scatter when the vector is known or
77: 2) have another way of generating a scatter context without a vector.*/
78: /*
79: This is not correct for a rectangular matrix mbd->rmap.N?
80: */
81: VecCreateMPI(mat->comm,mat->rmap.n,mat->cmap.N,&gvec);
83: /* generate the scatter context */
84: VecScatterCreate(gvec,from,mbd->lvec,to,&mbd->Mvctx);
85: PetscLogObjectParent(mat,mbd->Mvctx);
86: PetscLogObjectParent(mat,mbd->lvec);
87: PetscLogObjectParent(mat,to);
88: PetscLogObjectParent(mat,from);
89: PetscLogObjectParent(mat,gvec);
91: ISDestroy(to);
92: ISDestroy(from);
93: VecDestroy(gvec);
94: return(0);
95: }