Actual source code: ido.c
1: /*$Id: ido.c,v 1.13 2001/03/23 23:22:57 balay Exp $*/
2: /* ido.f -- translated by f2c (version of 25 March 1992 12:58:56).*/
4: #include petsc.h
5: #include src/mat/color/color.h
7: static int c_n1 = -1;
11: int MINPACKido(int *m,int * n,int * indrow,int * jpntr,int * indcol,int * ipntr,int * ndeg,
12: int *list,int *maxclq, int *iwa1, int *iwa2, int *iwa3, int *iwa4)
13: {
14: /* System generated locals */
15: int i__1, i__2, i__3, i__4;
17: /* Local variables */
18: int jcol = 0, ncomp = 0, ic, ip, jp, ir, maxinc, numinc, numord, maxlst, numwgt, numlst;
20: /* Given the sparsity pattern of an m by n matrix A, this */
21: /* subroutine determines an incidence-degree ordering of the */
22: /* columns of A. */
23: /* The incidence-degree ordering is defined for the loopless */
24: /* graph G with vertices a(j), j = 1,2,...,n where a(j) is the */
25: /* j-th column of A and with edge (a(i),a(j)) if and only if */
26: /* columns i and j have a non-zero in the same row position. */
27: /* The incidence-degree ordering is determined recursively by */
28: /* letting list(k), k = 1,...,n be a column with maximal */
29: /* incidence to the subgraph spanned by the ordered columns. */
30: /* Among all the columns of maximal incidence, ido chooses a */
31: /* column of maximal degree. */
32: /* The subroutine statement is */
33: /* subroutine ido(m,n,indrow,jpntr,indcol,ipntr,ndeg,list, */
34: /* maxclq,iwa1,iwa2,iwa3,iwa4) */
35: /* where */
36: /* m is a positive integer input variable set to the number */
37: /* of rows of A. */
38: /* n is a positive integer input variable set to the number */
39: /* of columns of A. */
40: /* indrow is an integer input array which contains the row */
41: /* indices for the non-zeroes in the matrix A. */
42: /* jpntr is an integer input array of length n + 1 which */
43: /* specifies the locations of the row indices in indrow. */
44: /* The row indices for column j are */
45: /* indrow(k), k = jpntr(j),...,jpntr(j+1)-1. */
46: /* Note that jpntr(n+1)-1 is then the number of non-zero */
47: /* elements of the matrix A. */
48: /* indcol is an integer input array which contains the */
49: /* column indices for the non-zeroes in the matrix A. */
50: /* ipntr is an integer input array of length m + 1 which */
51: /* specifies the locations of the column indices in indcol. */
52: /* The column indices for row i are */
53: /* indcol(k), k = ipntr(i),...,ipntr(i+1)-1. */
54: /* Note that ipntr(m+1)-1 is then the number of non-zero */
55: /* elements of the matrix A. */
56: /* ndeg is an integer input array of length n which specifies */
57: /* the degree sequence. The degree of the j-th column */
58: /* of A is ndeg(j). */
59: /* list is an integer output array of length n which specifies */
60: /* the incidence-degree ordering of the columns of A. The j-th */
61: /* column in this order is list(j). */
62: /* maxclq is an integer output variable set to the size */
63: /* of the largest clique found during the ordering. */
64: /* iwa1,iwa2,iwa3, and iwa4 are integer work arrays of length n. */
65: /* Subprograms called */
66: /* MINPACK-supplied ... numsrt */
67: /* FORTRAN-supplied ... max */
68: /* Argonne National Laboratory. MINPACK Project. August 1984. */
69: /* Thomas F. Coleman, Burton S. Garbow, Jorge J. More' */
71: /* Sort the degree sequence. */
74: /* Parameter adjustments */
75: --iwa4;
76: --iwa3;
77: --iwa2;
78: --list;
79: --ndeg;
80: --ipntr;
81: --indcol;
82: --jpntr;
83: --indrow;
85: /* Function Body */
86: i__1 = *n - 1;
87: MINPACKnumsrt(n, &i__1, &ndeg[1], &c_n1, &iwa4[1], &iwa2[1], &iwa3[1]);
89: /* Initialization block. */
90: /* Create a doubly-linked list to access the incidences of the */
91: /* columns. The pointers for the linked list are as follows. */
92: /* Each un-ordered column ic is in a list (the incidence list) */
93: /* of columns with the same incidence. */
94: /* iwa1(numinc) is the first column in the numinc list */
95: /* unless iwa1(numinc) = 0. In this case there are */
96: /* no columns in the numinc list. */
97: /* iwa2(ic) is the column before ic in the incidence list */
98: /* unless iwa2(ic) = 0. In this case ic is the first */
99: /* column in this incidence list. */
100: /* iwa3(ic) is the column after ic in the incidence list */
101: /* unless iwa3(ic) = 0. In this case ic is the last */
102: /* column in this incidence list. */
103: /* If ic is an un-ordered column, then list(ic) is the */
104: /* incidence of ic to the graph induced by the ordered */
105: /* columns. If jcol is an ordered column, then list(jcol) */
106: /* is the incidence-degree order of column jcol. */
108: maxinc = 0;
109: for (jp = *n; jp >= 1; --jp) {
110: ic = iwa4[jp];
111: iwa1[*n - jp] = 0;
112: iwa2[ic] = 0;
113: iwa3[ic] = iwa1[0];
114: if (iwa1[0] > 0) {
115: iwa2[iwa1[0]] = ic;
116: }
117: iwa1[0] = ic;
118: iwa4[jp] = 0;
119: list[jp] = 0;
120: }
122: /* Determine the maximal search length for the list */
123: /* of columns of maximal incidence. */
125: maxlst = 0;
126: i__1 = *m;
127: for (ir = 1; ir <= i__1; ++ir) {
128: /* Computing 2nd power */
129: i__2 = ipntr[ir + 1] - ipntr[ir];
130: maxlst += i__2 * i__2;
131: }
132: maxlst /= *n;
133: *maxclq = 0;
134: numord = 1;
136: /* Beginning of iteration loop. */
138: L30:
140: /* Choose a column jcol of maximal degree among the */
141: /* columns of maximal incidence maxinc. */
143: L40:
144: jp = iwa1[maxinc];
145: if (jp > 0) {
146: goto L50;
147: }
148: --maxinc;
149: goto L40;
150: L50:
151: numwgt = -1;
152: i__1 = maxlst;
153: for (numlst = 1; numlst <= i__1; ++numlst) {
154: if (ndeg[jp] > numwgt) {
155: numwgt = ndeg[jp];
156: jcol = jp;
157: }
158: jp = iwa3[jp];
159: if (jp <= 0) {
160: goto L70;
161: }
162: }
163: L70:
164: list[jcol] = numord;
166: /* Update the size of the largest clique */
167: /* found during the ordering. */
169: if (maxinc == 0) {
170: ncomp = 0;
171: }
172: ++ncomp;
173: if (maxinc + 1 == ncomp) {
174: *maxclq = PetscMax(*maxclq,ncomp);
175: }
177: /* Termination test. */
179: ++numord;
180: if (numord > *n) {
181: goto L100;
182: }
184: /* Delete column jcol from the maxinc list. */
186: if (iwa2[jcol] == 0) {
187: iwa1[maxinc] = iwa3[jcol];
188: } else {
189: iwa3[iwa2[jcol]] = iwa3[jcol];
190: }
191: if (iwa3[jcol] > 0) {
192: iwa2[iwa3[jcol]] = iwa2[jcol];
193: }
195: /* Find all columns adjacent to column jcol. */
197: iwa4[jcol] = *n;
199: /* Determine all positions (ir,jcol) which correspond */
200: /* to non-zeroes in the matrix. */
202: i__1 = jpntr[jcol + 1] - 1;
203: for (jp = jpntr[jcol]; jp <= i__1; ++jp) {
204: ir = indrow[jp];
206: /* For each row ir, determine all positions (ir,ic) */
207: /* which correspond to non-zeroes in the matrix. */
209: i__2 = ipntr[ir + 1] - 1;
210: for (ip = ipntr[ir]; ip <= i__2; ++ip) {
211: ic = indcol[ip];
213: /* Array iwa4 marks columns which are adjacent to */
214: /* column jcol. */
216: if (iwa4[ic] < numord) {
217: iwa4[ic] = numord;
219: /* Update the pointers to the current incidence lists. */
221: numinc = list[ic];
222: ++list[ic];
223: /* Computing MAX */
224: i__3 = maxinc, i__4 = list[ic];
225: maxinc = PetscMax(i__3,i__4);
227: /* Delete column ic from the numinc list. */
229: if (iwa2[ic] == 0) {
230: iwa1[numinc] = iwa3[ic];
231: } else {
232: iwa3[iwa2[ic]] = iwa3[ic];
233: }
234: if (iwa3[ic] > 0) {
235: iwa2[iwa3[ic]] = iwa2[ic];
236: }
238: /* Add column ic to the numinc+1 list. */
240: iwa2[ic] = 0;
241: iwa3[ic] = iwa1[numinc + 1];
242: if (iwa1[numinc + 1] > 0) {
243: iwa2[iwa1[numinc + 1]] = ic;
244: }
245: iwa1[numinc + 1] = ic;
246: }
247: }
248: }
250: /* End of iteration loop. */
252: goto L30;
253: L100:
255: /* Invert the array list. */
257: i__1 = *n;
258: for (jcol = 1; jcol <= i__1; ++jcol) {
259: iwa2[list[jcol]] = jcol;
260: }
261: i__1 = *n;
262: for (jp = 1; jp <= i__1; ++jp) {
263: list[jp] = iwa2[jp];
264: }
265: return(0);
266: }