Actual source code: sro.c
2: #include <../src/mat/impls/baij/seq/baij.h>
3: #include <../src/mat/impls/sbaij/seq/sbaij.h>
5: /*
6: This function is used before applying a
7: symmetric reordering to matrix A that is
8: in SBAIJ format.
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
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).
27: -- output: new index set (inew, jnew) for A and a map a2anew that maps
28: values a to anew, such that all
29: nonzero A_(perm(i),iperm(k)) will be stored in the upper triangle.
30: Note: matrix A is not permuted by this function!
31: */
32: PetscErrorCode MatReorderingSeqSBAIJ(Mat A, IS perm)
33: {
34: Mat_SeqSBAIJ *a = (Mat_SeqSBAIJ *)A->data;
35: const PetscInt mbs = a->mbs;
37: PetscFunctionBegin;
38: if (!mbs) PetscFunctionReturn(PETSC_SUCCESS);
39: SETERRQ(PETSC_COMM_SELF, PETSC_ERR_SUP, "Matrix reordering is not supported for sbaij matrix. Use aij format");
40: #if 0
41: const PetscInt *rip,*riip;
42: PetscInt *ai,*aj,*r;
43: PetscInt *nzr,nz,jmin,jmax,j,k,ajk,i;
44: IS iperm; /* inverse of perm */
45: PetscCall(ISGetIndices(perm,&rip));
47: PetscCall(ISInvertPermutation(perm,PETSC_DECIDE,&iperm));
48: PetscCall(ISGetIndices(iperm,&riip));
50: for (i=0; i<mbs; i++) {
51: PetscCheck(rip[i] == riip[i],PETSC_COMM_SELF,PETSC_ERR_ARG_INCOMP,"Non-symmetric permutation, use symmetric permutation for symmetric matrices");
52: }
53: PetscCall(ISRestoreIndices(iperm,&riip));
54: PetscCall(ISDestroy(&iperm));
56: if (!a->inew) {
57: PetscCall(PetscMalloc2(mbs+1,&ai, 2*a->i[mbs],&aj));
58: } else {
59: ai = a->inew; aj = a->jnew;
60: }
61: PetscCall(PetscArraycpy(ai,a->i,mbs+1));
62: PetscCall(PetscArraycpy(aj,a->j,a->i[mbs]));
64: /*
65: Phase 1: Find row index r in which to store each nonzero.
66: Initialize count of nonzeros to be stored in each row (nzr).
67: At the end of this phase, a nonzero a(*,*)=a(r(),aj())
68: s.t. a(perm(r),perm(aj)) will fall into upper triangle part.
69: */
71: PetscCall(PetscMalloc1(mbs,&nzr));
72: PetscCall(PetscMalloc1(ai[mbs],&r));
73: for (i=0; i<mbs; i++) nzr[i] = 0;
74: for (i=0; i<ai[mbs]; i++) r[i] = 0;
76: /* for each nonzero element */
77: for (i=0; i<mbs; i++) {
78: nz = ai[i+1] - ai[i];
79: j = ai[i];
80: /* printf("nz = %d, j=%d\n",nz,j); */
81: while (nz--) {
82: /* --- find row (=r[j]) and column (=aj[j]) in which to store a[j] ...*/
83: k = aj[j]; /* col. index */
84: /* printf("nz = %d, k=%d\n", nz,k); */
85: /* for entry that will be permuted into lower triangle, swap row and col. index */
86: if (rip[k] < rip[i]) aj[j] = i;
87: else k = i;
89: r[j] = k; j++;
90: nzr[k]++; /* increment count of nonzeros in that row */
91: }
92: }
94: /* Phase 2: Find new ai and permutation to apply to (aj,a).
95: Determine pointers (r) to delimit rows in permuted (aj,a).
96: Note: r is different from r used in phase 1.
97: At the end of this phase, (aj[j],a[j]) will be stored in
98: (aj[r(j)],a[r(j)]).
99: */
100: for (i=0; i<mbs; i++) {
101: ai[i+1] = ai[i] + nzr[i];
102: nzr[i] = ai[i+1];
103: }
105: /* determine where each (aj[j], a[j]) is stored in new (aj,a)
106: for each nonzero element (in reverse order) */
107: jmin = ai[0]; jmax = ai[mbs];
108: nz = jmax - jmin;
109: j = jmax-1;
110: while (nz--) {
111: i = r[j]; /* row value */
112: if (aj[j] == i) r[j] = ai[i]; /* put diagonal nonzero at beginning of row */
113: else { /* put off-diagonal nonzero in last unused location in row */
114: nzr[i]--; r[j] = nzr[i];
115: }
116: j--;
117: }
119: a->a2anew = aj + ai[mbs];
120: PetscCall(PetscArraycpy(a->a2anew,r,ai[mbs]));
122: /* Phase 3: permute (aj,a) to upper triangular form (wrt new ordering) */
123: for (j=jmin; j<jmax; j++) {
124: while (r[j] != j) {
125: k = r[j]; r[j] = r[k]; r[k] = k;
126: ajk = aj[k]; aj[k] = aj[j]; aj[j] = ajk;
127: /* ak = aa[k]; aa[k] = aa[j]; aa[j] = ak; */
128: }
129: }
130: PetscCall(ISRestoreIndices(perm,&rip));
132: a->inew = ai;
133: a->jnew = aj;
135: PetscCall(ISDestroy(&a->row));
136: PetscCall(ISDestroy(&a->icol));
137: PetscCall(PetscObjectReference((PetscObject)perm));
138: PetscCall(ISDestroy(&a->row));
139: a->row = perm;
140: PetscCall(PetscObjectReference((PetscObject)perm));
141: PetscCall(ISDestroy(&a->icol));
142: a->icol = perm;
144: PetscCall(PetscFree(nzr));
145: PetscCall(PetscFree(r));
146: PetscFunctionReturn(PETSC_SUCCESS);
147: #endif
148: }