Actual source code: mmbdiag.c
1: /*$Id: mmbdiag.c,v 1.40 2001/03/23 23:22:05 balay Exp $*/
3: /*
4: Support for the MPIBDIAG matrix-vector multiply
5: */
6: #include src/mat/impls/bdiag/mpi/mpibdiag.h
7: #include src/vec/vecimpl.h
9: int MatSetUpMultiply_MPIBDiag(Mat mat)
10: {
11: Mat_MPIBDiag *mbd = (Mat_MPIBDiag*)mat->data;
12: Mat_SeqBDiag *lmbd = (Mat_SeqBDiag*)mbd->A->data;
13: int ierr,N = mat->N,*indices,*garray,ec=0;
14: int bs = lmbd->bs,d,i,j,diag;
15: IS to,from;
16: Vec gvec;
19: /* We make an array as long as the number of columns */
20: /* mark those columns that are in mbd->A */
21: PetscMalloc((N+1)*sizeof(int),&indices);
22: ierr = PetscMemzero(indices,N*sizeof(int));
24: if (bs == 1) {
25: for (d=0; d<lmbd->nd; d++) {
26: diag = lmbd->diag[d];
27: if (diag > 0) { /* col = loc */
28: for (j=0; j<lmbd->bdlen[d]; j++) {
29: if (!indices[j]) ec++;
30: indices[j] = 1;
31: }
32: } else { /* col = loc-diag */
33: for (j=0; j<lmbd->bdlen[d]; j++) {
34: if (!indices[j-diag]) ec++;
35: indices[j-diag] = 1;
36: }
37: }
38: }
39: } else {
40: for (d=0; d<lmbd->nd; d++) {
41: diag = lmbd->diag[d];
42: if (diag > 0) { /* col = loc */
43: for (j=0; j<lmbd->bdlen[d]; j++) {
44: if (!indices[bs*j]) ec += bs;
45: for (i=0; i<bs; i++) indices[bs*j+i] = 1;
46: }
47: } else { /* col = loc-diag */
48: for (j=0; j<lmbd->bdlen[d]; j++) {
49: if (!indices[bs*(j-diag)]) ec += bs;
50: for (i=0; i<bs; i++) indices[bs*(j-diag)+i] = 1;
51: }
52: }
53: }
54: }
56: /* form array of columns we need */
57: PetscMalloc((ec+1)*sizeof(int),&garray);
58: ec = 0;
59: for (i=0; i<N; i++) {
60: if (indices[i]) garray[ec++] = i;
61: }
62: PetscFree(indices);
64: /* create local vector that is used to scatter into */
65: VecCreateSeq(PETSC_COMM_SELF,N,&mbd->lvec);
67: /* create temporary index set for building scatter-gather */
68: ISCreateGeneral(mat->comm,ec,garray,&from);
69: ISCreateGeneral(PETSC_COMM_SELF,ec,garray,&to);
70: PetscFree(garray);
72: /* create temporary global vector to generate scatter context */
73: /* this is inefficient, but otherwise we must do either
74: 1) save garray until the first actual scatter when the vector is known or
75: 2) have another way of generating a scatter context without a vector.*/
76: /*
77: This is not correct for a rectangular matrix mbd->m?
78: */
79: VecCreateMPI(mat->comm,mat->m,mat->N,&gvec);
81: /* generate the scatter context */
82: VecScatterCreate(gvec,from,mbd->lvec,to,&mbd->Mvctx);
83: PetscLogObjectParent(mat,mbd->Mvctx);
84: PetscLogObjectParent(mat,mbd->lvec);
85: PetscLogObjectParent(mat,to);
86: PetscLogObjectParent(mat,from);
87: PetscLogObjectParent(mat,gvec);
89: ISDestroy(to);
90: ISDestroy(from);
91: VecDestroy(gvec);
92: return(0);
93: }