1 2 #include <../src/mat/impls/baij/seq/baij.h> 3 #include <../src/mat/impls/sbaij/seq/sbaij.h> 4 5 /* 6 This function is used before applying a 7 symmetric reordering to matrix A that is 8 in SBAIJ format. 9 10 The permutation is assumed to be symmetric, i.e., 11 P = P^T (= inv(P)), 12 so the permuted matrix P*A*inv(P)=P*A*P^T is ensured to be symmetric. 13 - a wrong assumption! This code needs rework! -- Hong 14 15 The function is modified from sro.f of YSMP. The description from YSMP: 16 C THE NONZERO ENTRIES OF THE MATRIX M ARE ASSUMED TO BE STORED 17 C SYMMETRICALLY IN (IA,JA,A) FORMAT (I.E., NOT BOTH M(I,J) AND M(J,I) 18 C ARE STORED IF I NE J). 19 C 20 C SRO DOES NOT REARRANGE THE ORDER OF THE ROWS, BUT DOES MOVE 21 C NONZEROES FROM ONE ROW TO ANOTHER TO ENSURE THAT IF M(I,J) WILL BE 22 C IN THE UPPER TRIANGLE OF M WITH RESPECT TO THE NEW ORDERING, THEN 23 C M(I,J) IS STORED IN ROW I (AND THUS M(J,I) IS NOT STORED); WHEREAS 24 C IF M(I,J) WILL BE IN THE STRICT LOWER TRIANGLE OF M, THEN M(J,I) IS 25 C STORED IN ROW J (AND THUS M(I,J) IS NOT STORED). 26 27 28 -- output: new index set (inew, jnew) for A and a map a2anew that maps 29 values a to anew, such that all 30 nonzero A_(perm(i),iperm(k)) will be stored in the upper triangle. 31 Note: matrix A is not permuted by this function! 32 */ 33 PetscErrorCode MatReorderingSeqSBAIJ(Mat A,IS perm) 34 { 35 Mat_SeqSBAIJ *a=(Mat_SeqSBAIJ*)A->data; 36 const PetscInt mbs=a->mbs; 37 38 PetscFunctionBegin; 39 if (!mbs) PetscFunctionReturn(0); 40 SETERRQ(PETSC_COMM_SELF,PETSC_ERR_SUP,"Matrix reordering is not supported for sbaij matrix. Use aij format"); 41 #if 0 42 PetscErrorCode ierr; 43 const PetscInt *rip,*riip; 44 PetscInt *ai,*aj,*r; 45 PetscInt *nzr,nz,jmin,jmax,j,k,ajk,i; 46 IS iperm; /* inverse of perm */ 47 ierr = ISGetIndices(perm,&rip);CHKERRQ(ierr); 48 49 ierr = ISInvertPermutation(perm,PETSC_DECIDE,&iperm);CHKERRQ(ierr); 50 ierr = ISGetIndices(iperm,&riip);CHKERRQ(ierr); 51 52 for (i=0; i<mbs; i++) { 53 if (rip[i] != riip[i]) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_INCOMP,"Non-symmetric permutation, use symmetric permutation for symmetric matrices"); 54 } 55 ierr = ISRestoreIndices(iperm,&riip);CHKERRQ(ierr); 56 ierr = ISDestroy(&iperm);CHKERRQ(ierr); 57 58 if (!a->inew) { 59 ierr = PetscMalloc2(mbs+1,&ai, 2*a->i[mbs],&aj);CHKERRQ(ierr); 60 } else { 61 ai = a->inew; aj = a->jnew; 62 } 63 ierr = PetscMemcpy(ai,a->i,(mbs+1)*sizeof(PetscInt));CHKERRQ(ierr); 64 ierr = PetscMemcpy(aj,a->j,(a->i[mbs])*sizeof(PetscInt));CHKERRQ(ierr); 65 66 /* 67 Phase 1: Find row index r in which to store each nonzero. 68 Initialize count of nonzeros to be stored in each row (nzr). 69 At the end of this phase, a nonzero a(*,*)=a(r(),aj()) 70 s.t. a(perm(r),perm(aj)) will fall into upper triangle part. 71 */ 72 73 ierr = PetscMalloc1(mbs,&nzr);CHKERRQ(ierr); 74 ierr = PetscMalloc1(ai[mbs],&r);CHKERRQ(ierr); 75 for (i=0; i<mbs; i++) nzr[i] = 0; 76 for (i=0; i<ai[mbs]; i++) r[i] = 0; 77 78 /* for each nonzero element */ 79 for (i=0; i<mbs; i++) { 80 nz = ai[i+1] - ai[i]; 81 j = ai[i]; 82 /* printf("nz = %d, j=%d\n",nz,j); */ 83 while (nz--) { 84 /* --- find row (=r[j]) and column (=aj[j]) in which to store a[j] ...*/ 85 k = aj[j]; /* col. index */ 86 /* printf("nz = %d, k=%d\n", nz,k); */ 87 /* for entry that will be permuted into lower triangle, swap row and col. index */ 88 if (rip[k] < rip[i]) aj[j] = i; 89 else k = i; 90 91 r[j] = k; j++; 92 nzr[k]++; /* increment count of nonzeros in that row */ 93 } 94 } 95 96 /* Phase 2: Find new ai and permutation to apply to (aj,a). 97 Determine pointers (r) to delimit rows in permuted (aj,a). 98 Note: r is different from r used in phase 1. 99 At the end of this phase, (aj[j],a[j]) will be stored in 100 (aj[r(j)],a[r(j)]). 101 */ 102 for (i=0; i<mbs; i++) { 103 ai[i+1] = ai[i] + nzr[i]; 104 nzr[i] = ai[i+1]; 105 } 106 107 /* determine where each (aj[j], a[j]) is stored in new (aj,a) 108 for each nonzero element (in reverse order) */ 109 jmin = ai[0]; jmax = ai[mbs]; 110 nz = jmax - jmin; 111 j = jmax-1; 112 while (nz--) { 113 i = r[j]; /* row value */ 114 if (aj[j] == i) r[j] = ai[i]; /* put diagonal nonzero at beginning of row */ 115 else { /* put off-diagonal nonzero in last unused location in row */ 116 nzr[i]--; r[j] = nzr[i]; 117 } 118 j--; 119 } 120 121 a->a2anew = aj + ai[mbs]; 122 ierr = PetscMemcpy(a->a2anew,r,ai[mbs]*sizeof(PetscInt));CHKERRQ(ierr); 123 124 /* Phase 3: permute (aj,a) to upper triangular form (wrt new ordering) */ 125 for (j=jmin; j<jmax; j++) { 126 while (r[j] != j) { 127 k = r[j]; r[j] = r[k]; r[k] = k; 128 ajk = aj[k]; aj[k] = aj[j]; aj[j] = ajk; 129 /* ak = aa[k]; aa[k] = aa[j]; aa[j] = ak; */ 130 } 131 } 132 ierr= ISRestoreIndices(perm,&rip);CHKERRQ(ierr); 133 134 a->inew = ai; 135 a->jnew = aj; 136 137 ierr = ISDestroy(&a->row);CHKERRQ(ierr); 138 ierr = ISDestroy(&a->icol);CHKERRQ(ierr); 139 ierr = PetscObjectReference((PetscObject)perm);CHKERRQ(ierr); 140 ierr = ISDestroy(&a->row);CHKERRQ(ierr); 141 a->row = perm; 142 ierr = PetscObjectReference((PetscObject)perm);CHKERRQ(ierr); 143 ierr = ISDestroy(&a->icol);CHKERRQ(ierr); 144 a->icol = perm; 145 146 ierr = PetscFree(nzr);CHKERRQ(ierr); 147 ierr = PetscFree(r);CHKERRQ(ierr); 148 PetscFunctionReturn(0); 149 #endif 150 } 151 152 153