Actual source code: ido.c
1: #define PETSCMAT_DLL
2: /* ido.f -- translated by f2c (version of 25 March 1992 12:58:56).*/
4: #include ../src/mat/color/color.h
6: static PetscInt c_n1 = -1;
10: PetscErrorCode MINPACKido(PetscInt *m,PetscInt * n,PetscInt * indrow,PetscInt * jpntr,PetscInt * indcol,PetscInt * ipntr,PetscInt * ndeg,
11: PetscInt *list,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 = 0, ncomp = 0, ic, ip, jp, ir, maxinc, numinc, numord, maxlst, numwgt, numlst;
19: /* Given the sparsity pattern of an m by n matrix A, this */
20: /* subroutine determines an incidence-degree ordering of the */
21: /* columns of A. */
22: /* The incidence-degree 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 incidence-degree ordering is determined recursively by */
27: /* letting list(k), k = 1,...,n be a column with maximal */
28: /* incidence to the subgraph spanned by the ordered columns. */
29: /* Among all the columns of maximal incidence, ido chooses a */
30: /* column of maximal degree. */
31: /* The subroutine statement is */
32: /* subroutine ido(m,n,indrow,jpntr,indcol,ipntr,ndeg,list, */
33: /* maxclq,iwa1,iwa2,iwa3,iwa4) */
34: /* where */
35: /* m is a positive integer input variable set to the number */
36: /* of rows of A. */
37: /* n is a positive integer input variable set to the number */
38: /* of columns of A. */
39: /* indrow is an integer input array which contains the row */
40: /* indices for the non-zeroes in the matrix A. */
41: /* jpntr is an integer input array of length n + 1 which */
42: /* specifies the locations of the row indices in indrow. */
43: /* The row indices for column j are */
44: /* indrow(k), k = jpntr(j),...,jpntr(j+1)-1. */
45: /* Note that jpntr(n+1)-1 is then the number of non-zero */
46: /* elements of the matrix A. */
47: /* indcol is an integer input array which contains the */
48: /* column indices for the non-zeroes in the matrix A. */
49: /* ipntr is an integer input array of length m + 1 which */
50: /* specifies the locations of the column indices in indcol. */
51: /* The column indices for row i are */
52: /* indcol(k), k = ipntr(i),...,ipntr(i+1)-1. */
53: /* Note that ipntr(m+1)-1 is then the number of non-zero */
54: /* elements of the matrix A. */
55: /* ndeg is an integer input array of length n which specifies */
56: /* the degree sequence. The degree of the j-th column */
57: /* of A is ndeg(j). */
58: /* list is an integer output array of length n which specifies */
59: /* the incidence-degree ordering of the columns of A. The j-th */
60: /* column in this order is list(j). */
61: /* maxclq is an integer output variable set to the size */
62: /* of the largest clique found during the ordering. */
63: /* iwa1,iwa2,iwa3, and iwa4 are integer work arrays of length n. */
64: /* Subprograms called */
65: /* MINPACK-supplied ... numsrt */
66: /* FORTRAN-supplied ... max */
67: /* Argonne National Laboratory. MINPACK Project. August 1984. */
68: /* Thomas F. Coleman, Burton S. Garbow, Jorge J. More' */
70: /* Sort the degree sequence. */
73: /* Parameter adjustments */
74: --iwa4;
75: --iwa3;
76: --iwa2;
77: --list;
78: --ndeg;
79: --ipntr;
80: --indcol;
81: --jpntr;
82: --indrow;
84: /* Function Body */
85: i__1 = *n - 1;
86: MINPACKnumsrt(n, &i__1, &ndeg[1], &c_n1, &iwa4[1], &iwa2[1], &iwa3[1]);
88: /* Initialization block. */
89: /* Create a doubly-linked list to access the incidences of the */
90: /* columns. The pointers for the linked list are as follows. */
91: /* Each un-ordered column ic is in a list (the incidence list) */
92: /* of columns with the same incidence. */
93: /* iwa1(numinc) is the first column in the numinc list */
94: /* unless iwa1(numinc) = 0. In this case there are */
95: /* no columns in the numinc list. */
96: /* iwa2(ic) is the column before ic in the incidence list */
97: /* unless iwa2(ic) = 0. In this case ic is the first */
98: /* column in this incidence list. */
99: /* iwa3(ic) is the column after ic in the incidence list */
100: /* unless iwa3(ic) = 0. In this case ic is the last */
101: /* column in this incidence list. */
102: /* If ic is an un-ordered column, then list(ic) is the */
103: /* incidence of ic to the graph induced by the ordered */
104: /* columns. If jcol is an ordered column, then list(jcol) */
105: /* is the incidence-degree order of column jcol. */
107: maxinc = 0;
108: for (jp = *n; jp >= 1; --jp) {
109: ic = iwa4[jp];
110: iwa1[*n - jp] = 0;
111: iwa2[ic] = 0;
112: iwa3[ic] = iwa1[0];
113: if (iwa1[0] > 0) {
114: iwa2[iwa1[0]] = ic;
115: }
116: iwa1[0] = ic;
117: iwa4[jp] = 0;
118: list[jp] = 0;
119: }
121: /* Determine the maximal search length for the list */
122: /* of columns of maximal incidence. */
124: maxlst = 0;
125: i__1 = *m;
126: for (ir = 1; ir <= i__1; ++ir) {
127: /* Computing 2nd power */
128: i__2 = ipntr[ir + 1] - ipntr[ir];
129: maxlst += i__2 * i__2;
130: }
131: maxlst /= *n;
132: *maxclq = 0;
133: numord = 1;
135: /* Beginning of iteration loop. */
137: L30:
139: /* Choose a column jcol of maximal degree among the */
140: /* columns of maximal incidence maxinc. */
142: L40:
143: jp = iwa1[maxinc];
144: if (jp > 0) {
145: goto L50;
146: }
147: --maxinc;
148: goto L40;
149: L50:
150: numwgt = -1;
151: i__1 = maxlst;
152: for (numlst = 1; numlst <= i__1; ++numlst) {
153: if (ndeg[jp] > numwgt) {
154: numwgt = ndeg[jp];
155: jcol = jp;
156: }
157: jp = iwa3[jp];
158: if (jp <= 0) {
159: goto L70;
160: }
161: }
162: L70:
163: list[jcol] = numord;
165: /* Update the size of the largest clique */
166: /* found during the ordering. */
168: if (!maxinc) {
169: ncomp = 0;
170: }
171: ++ncomp;
172: if (maxinc + 1 == ncomp) {
173: *maxclq = PetscMax(*maxclq,ncomp);
174: }
176: /* Termination test. */
178: ++numord;
179: if (numord > *n) {
180: goto L100;
181: }
183: /* Delete column jcol from the maxinc list. */
185: if (!iwa2[jcol]) {
186: iwa1[maxinc] = iwa3[jcol];
187: } else {
188: iwa3[iwa2[jcol]] = iwa3[jcol];
189: }
190: if (iwa3[jcol] > 0) {
191: iwa2[iwa3[jcol]] = iwa2[jcol];
192: }
194: /* Find all columns adjacent to column jcol. */
196: iwa4[jcol] = *n;
198: /* Determine all positions (ir,jcol) which correspond */
199: /* to non-zeroes in the matrix. */
201: i__1 = jpntr[jcol + 1] - 1;
202: for (jp = jpntr[jcol]; jp <= i__1; ++jp) {
203: ir = indrow[jp];
205: /* For each row ir, determine all positions (ir,ic) */
206: /* which correspond to non-zeroes in the matrix. */
208: i__2 = ipntr[ir + 1] - 1;
209: for (ip = ipntr[ir]; ip <= i__2; ++ip) {
210: ic = indcol[ip];
212: /* Array iwa4 marks columns which are adjacent to */
213: /* column jcol. */
215: if (iwa4[ic] < numord) {
216: iwa4[ic] = numord;
218: /* Update the pointers to the current incidence lists. */
220: numinc = list[ic];
221: ++list[ic];
222: /* Computing MAX */
223: i__3 = maxinc, i__4 = list[ic];
224: maxinc = PetscMax(i__3,i__4);
226: /* Delete column ic from the numinc list. */
228: if (!iwa2[ic]) {
229: iwa1[numinc] = iwa3[ic];
230: } else {
231: iwa3[iwa2[ic]] = iwa3[ic];
232: }
233: if (iwa3[ic] > 0) {
234: iwa2[iwa3[ic]] = iwa2[ic];
235: }
237: /* Add column ic to the numinc+1 list. */
239: iwa2[ic] = 0;
240: iwa3[ic] = iwa1[numinc + 1];
241: if (iwa1[numinc + 1] > 0) {
242: iwa2[iwa1[numinc + 1]] = ic;
243: }
244: iwa1[numinc + 1] = ic;
245: }
246: }
247: }
249: /* End of iteration loop. */
251: goto L30;
252: L100:
254: /* Invert the array list. */
256: i__1 = *n;
257: for (jcol = 1; jcol <= i__1; ++jcol) {
258: iwa2[list[jcol]] = jcol;
259: }
260: i__1 = *n;
261: for (jp = 1; jp <= i__1; ++jp) {
262: list[jp] = iwa2[jp];
263: }
264: return(0);
265: }