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