Actual source code: slo.c
1: #define PETSCMAT_DLL
3: /* slo.f -- translated by f2c (version of 25 March 1992 12:58:56).*/
5: #include petsc.h
6: #include src/mat/color/color.h
10: PetscErrorCode MINPACKslo(PetscInt *n,PetscInt * indrow,PetscInt * jpntr,PetscInt * indcol, PetscInt *ipntr, PetscInt *ndeg,PetscInt * list,
11: PetscInt * maxclq,PetscInt *iwa1,PetscInt * iwa2,PetscInt * iwa3,PetscInt * iwa4)
12: {
13: /* System generated locals */
14: PetscInt i__1, i__2, i__3, i__4;
16: /* Local variables */
17: PetscInt jcol, ic, ip, jp, ir, mindeg, numdeg, numord;
19: /* Given the sparsity pattern of an m by n matrix A, this */
20: /* subroutine determines the smallest-last ordering of the */
21: /* columns of A. */
22: /* The smallest-last ordering is defined for the loopless */
23: /* graph G with vertices a(j), j = 1,2,...,n where a(j) is the */
24: /* j-th column of A and with edge (a(i),a(j)) if and only if */
25: /* columns i and j have a non-zero in the same row position. */
26: /* The smallest-last ordering is determined recursively by */
27: /* letting list(k), k = n,...,1 be a column with least degree */
28: /* in the subgraph spanned by the un-ordered columns. */
29: /* Note that the value of m is not needed by slo and is */
30: /* therefore not present in the subroutine statement. */
31: /* The subroutine statement is */
32: /* subroutine slo(n,indrow,jpntr,indcol,ipntr,ndeg,list, */
33: /* maxclq,iwa1,iwa2,iwa3,iwa4) */
34: /* where */
35: /* n is a positive integer input variable set to the number */
36: /* of columns of A. */
37: /* indrow is an integer input array which contains the row */
38: /* indices for the non-zeroes in the matrix A. */
39: /* jpntr is an integer input array of length n + 1 which */
40: /* specifies the locations of the row indices in indrow. */
41: /* The row indices for column j are */
42: /* indrow(k), k = jpntr(j),...,jpntr(j+1)-1. */
43: /* Note that jpntr(n+1)-1 is then the number of non-zero */
44: /* elements of the matrix A. */
45: /* indcol is an integer input array which contains the */
46: /* column indices for the non-zeroes in the matrix A. */
47: /* ipntr is an integer input array of length m + 1 which */
48: /* specifies the locations of the column indices in indcol. */
49: /* The column indices for row i are */
50: /* indcol(k), k = ipntr(i),...,ipntr(i+1)-1. */
51: /* Note that ipntr(m+1)-1 is then the number of non-zero */
52: /* elements of the matrix A. */
53: /* ndeg is an integer input array of length n which specifies */
54: /* the degree sequence. The degree of the j-th column */
55: /* of A is ndeg(j). */
56: /* list is an integer output array of length n which specifies */
57: /* the smallest-last ordering of the columns of A. The j-th */
58: /* column in this order is list(j). */
59: /* maxclq is an integer output variable set to the size */
60: /* of the largest clique found during the ordering. */
61: /* iwa1,iwa2,iwa3, and iwa4 are integer work arrays of length n. */
62: /* Subprograms called */
63: /* FORTRAN-supplied ... min */
64: /* Argonne National Laboratory. MINPACK Project. August 1984. */
65: /* Thomas F. Coleman, Burton S. Garbow, Jorge J. More' */
68: /* Parameter adjustments */
69: --iwa4;
70: --iwa3;
71: --iwa2;
72: --list;
73: --ndeg;
74: --ipntr;
75: --indcol;
76: --jpntr;
77: --indrow;
79: /* Function Body */
80: mindeg = *n;
81: i__1 = *n;
82: for (jp = 1; jp <= i__1; ++jp) {
83: iwa1[jp - 1] = 0;
84: iwa4[jp] = *n;
85: list[jp] = ndeg[jp];
86: /* Computing MIN */
87: i__2 = mindeg, i__3 = ndeg[jp];
88: mindeg = PetscMin(i__2,i__3);
89: }
91: /* Create a doubly-linked list to access the degrees of the */
92: /* columns. The pointers for the linked list are as follows. */
94: /* Each un-ordered column ic is in a list (the degree list) */
95: /* of columns with the same degree. */
97: /* iwa1(numdeg) is the first column in the numdeg list */
98: /* unless iwa1(numdeg) = 0. In this case there are */
99: /* no columns in the numdeg list. */
101: /* iwa2(ic) is the column before ic in the degree list */
102: /* unless iwa2(ic) = 0. In this case ic is the first */
103: /* column in this degree list. */
105: /* iwa3(ic) is the column after ic in the degree list */
106: /* unless iwa3(ic) = 0. In this case ic is the last */
107: /* column in this degree list. */
109: /* If ic is an un-ordered column, then list(ic) is the */
110: /* degree of ic in the graph induced by the un-ordered */
111: /* columns. If jcol is an ordered column, then list(jcol) */
112: /* is the smallest-last order of column jcol. */
114: i__1 = *n;
115: for (jp = 1; jp <= i__1; ++jp) {
116: numdeg = ndeg[jp];
117: iwa2[jp] = 0;
118: iwa3[jp] = iwa1[numdeg];
119: if (iwa1[numdeg] > 0) {
120: iwa2[iwa1[numdeg]] = jp;
121: }
122: iwa1[numdeg] = jp;
123: }
124: *maxclq = 0;
125: numord = *n;
127: /* Beginning of iteration loop. */
129: L30:
131: /* Choose a column jcol of minimal degree mindeg. */
133: L40:
134: jcol = iwa1[mindeg];
135: if (jcol > 0) {
136: goto L50;
137: }
138: ++mindeg;
139: goto L40;
140: L50:
141: list[jcol] = numord;
143: /* Mark the size of the largest clique */
144: /* found during the ordering. */
146: if (mindeg + 1 == numord && !*maxclq) {
147: *maxclq = numord;
148: }
150: /* Termination test. */
152: --numord;
153: if (!numord) {
154: goto L80;
155: }
157: /* Delete column jcol from the mindeg list. */
159: iwa1[mindeg] = iwa3[jcol];
160: if (iwa3[jcol] > 0) {
161: iwa2[iwa3[jcol]] = 0;
162: }
164: /* Find all columns adjacent to column jcol. */
166: iwa4[jcol] = 0;
168: /* Determine all positions (ir,jcol) which correspond */
169: /* to non-zeroes in the matrix. */
171: i__1 = jpntr[jcol + 1] - 1;
172: for (jp = jpntr[jcol]; jp <= i__1; ++jp) {
173: ir = indrow[jp];
175: /* For each row ir, determine all positions (ir,ic) */
176: /* which correspond to non-zeroes in the matrix. */
178: i__2 = ipntr[ir + 1] - 1;
179: for (ip = ipntr[ir]; ip <= i__2; ++ip) {
180: ic = indcol[ip];
182: /* Array iwa4 marks columns which are adjacent to */
183: /* column jcol. */
185: if (iwa4[ic] > numord) {
186: iwa4[ic] = numord;
188: /* Update the pointers to the current degree lists. */
190: numdeg = list[ic];
191: --list[ic];
192: /* Computing MIN */
193: i__3 = mindeg, i__4 = list[ic];
194: mindeg = PetscMin(i__3,i__4);
196: /* Delete column ic from the numdeg list. */
198: if (!iwa2[ic]) {
199: iwa1[numdeg] = iwa3[ic];
200: } else {
201: iwa3[iwa2[ic]] = iwa3[ic];
202: }
203: if (iwa3[ic] > 0) {
204: iwa2[iwa3[ic]] = iwa2[ic];
205: }
207: /* Add column ic to the numdeg-1 list. */
209: iwa2[ic] = 0;
210: iwa3[ic] = iwa1[numdeg - 1];
211: if (iwa1[numdeg - 1] > 0) {
212: iwa2[iwa1[numdeg - 1]] = ic;
213: }
214: iwa1[numdeg - 1] = ic;
215: }
216: }
217: }
219: /* End of iteration loop. */
221: goto L30;
222: L80:
224: /* Invert the array list. */
226: i__1 = *n;
227: for (jcol = 1; jcol <= i__1; ++jcol) {
228: iwa2[list[jcol]] = jcol;
229: }
230: i__1 = *n;
231: for (jp = 1; jp <= i__1; ++jp) {
232: list[jp] = iwa2[jp];
233: }
234: return(0);
235: }