1 #ifndef lint 2 static char vcid[] = "$Id: mmaij.c,v 1.11 1995/06/08 03:09:29 bsmith Exp bsmith $"; 3 #endif 4 5 6 /* 7 Support for the parallel AIJ matrix vector multiply 8 */ 9 #include "mpiaij.h" 10 #include "vec/vecimpl.h" 11 #include "../seq/aij.h" 12 13 int MatSetUpMultiply_MPIAIJ(Mat mat) 14 { 15 Mat_MPIAIJ *aij = (Mat_MPIAIJ *) mat->data; 16 Mat_AIJ *B = (Mat_AIJ *) (aij->B->data); 17 int N = aij->N,i,j,*indices,*aj = B->j; 18 int ierr,ec = 0,*garray; 19 IS from,to; 20 Vec gvec; 21 22 /* For the first stab we make an array as long as the number of columns */ 23 /* mark those columns that are in aij->B */ 24 indices = (int *) PETSCMALLOC( N*sizeof(int) ); CHKPTRQ(indices); 25 PETSCMEMSET(indices,0,N*sizeof(int)); 26 for ( i=0; i<B->m; i++ ) { 27 for ( j=0; j<B->ilen[i]; j++ ) { 28 if (!indices[aj[B->i[i] - 1 + j]-1]) ec++; 29 indices[aj[B->i[i] - 1 + j]-1] = 1;} 30 } 31 32 /* form array of columns we need */ 33 garray = (int *) PETSCMALLOC( (ec+1)*sizeof(int) ); CHKPTRQ(garray); 34 ec = 0; 35 for ( i=0; i<N; i++ ) { 36 if (indices[i]) garray[ec++] = i; 37 } 38 39 /* make indices now point into garray */ 40 for ( i=0; i<ec; i++ ) { 41 indices[garray[i]] = i+1; 42 } 43 44 /* compact out the extra columns in B */ 45 for ( i=0; i<B->m; i++ ) { 46 for ( j=0; j<B->ilen[i]; j++ ) { 47 aj[B->i[i] - 1 + j] = indices[aj[B->i[i] - 1 + j]-1]; 48 } 49 } 50 B->n = ec; 51 PETSCFREE(indices); 52 53 /* create local vector that is used to scatter into */ 54 ierr = VecCreateSequential(MPI_COMM_SELF,ec,&aij->lvec); CHKERRQ(ierr); 55 56 /* create two temporary Index sets for build scatter gather */ 57 ierr = ISCreateSequential(MPI_COMM_SELF,ec,garray,&from); CHKERRQ(ierr); 58 ierr = ISCreateStrideSequential(MPI_COMM_SELF,ec,0,1,&to); CHKERRQ(ierr); 59 60 /* create temporary global vector to generate scatter context */ 61 /* this is inefficient, but otherwise we must do either 62 1) save garray until the first actual scatter when the vector is known or 63 2) have another way of generating a scatter context without a vector.*/ 64 ierr = VecCreateMPI(mat->comm,aij->n,aij->N,&gvec); CHKERRQ(ierr); 65 66 /* gnerate the scatter context */ 67 ierr = VecScatterCtxCreate(gvec,from,aij->lvec,to,&aij->Mvctx); CHKERRQ(ierr); 68 PLogObjectParent(mat,aij->Mvctx); 69 PLogObjectParent(mat,aij->lvec); 70 aij->garray = garray; 71 ierr = ISDestroy(from); CHKERRQ(ierr); 72 ierr = ISDestroy(to); CHKERRQ(ierr); 73 ierr = VecDestroy(gvec); 74 return 0; 75 } 76 77 78 /* 79 Takes the local part of an already assembled MPIAIJ matrix 80 and disassembles it. This is to allow new nonzeros into the matrix 81 that require more communication in the matrix vector multiply. 82 Thus certain data-structures must be rebuilt. 83 84 Kind of slow! But that's what application programmers get when 85 they are sloppy. 86 */ 87 int DisAssemble_MPIAIJ(Mat A) 88 { 89 Mat_MPIAIJ *aij = (Mat_MPIAIJ *) A->data; 90 Mat B = aij->B,Bnew; 91 Mat_AIJ *Baij = (Mat_AIJ*)B->data; 92 int ierr,i,j,m=Baij->m,n = aij->N,col,ct = 0,*garray = aij->garray; 93 Scalar v; 94 95 fprintf(stderr,"Warning: you are adding tricky new nonzeros\n"); 96 97 /* free stuff related to matrix-vec multiply */ 98 ierr = VecDestroy(aij->lvec); CHKERRQ(ierr); aij->lvec = 0; 99 ierr = VecScatterCtxDestroy(aij->Mvctx); CHKERRQ(ierr); aij->Mvctx = 0; 100 PETSCFREE(aij->colmap); aij->colmap = 0; 101 102 /* make sure that B is assembled so we can access its values */ 103 ierr = MatAssemblyBegin(B,FINAL_ASSEMBLY); CHKERRQ(ierr); 104 MatAssemblyEnd(B,FINAL_ASSEMBLY); CHKERRQ(ierr); 105 106 /* invent new B and copy stuff over */ 107 ierr = MatCreateSequentialAIJ(MPI_COMM_SELF,m,n,0,0,&Bnew); CHKERRQ(ierr); 108 for ( i=0; i<m; i++ ) { 109 for ( j=Baij->i[i]-1; j<Baij->i[i+1]-1; j++ ) { 110 col = garray[Baij->j[ct]-1]; 111 v = Baij->a[ct++]; 112 ierr = MatSetValues(Bnew,1,&i,1,&col,&v,INSERTVALUES); CHKERRQ(ierr); 113 } 114 } 115 PETSCFREE(aij->garray); aij->garray = 0; 116 ierr = MatDestroy(B); CHKERRQ(ierr); 117 aij->B = Bnew; 118 aij->assembled = 0; 119 return 0; 120 } 121 122