2: /* slo.f -- translated by f2c (version of 25 March 1992 12:58:56).*/
4: #include <../src/mat/color/impls/minpack/color.h> 6: PetscErrorCode MINPACKslo(PetscInt *n,const PetscInt * indrow,const PetscInt * jpntr,const PetscInt * indcol,const PetscInt *ipntr, PetscInt *ndeg,PetscInt * list, 7: PetscInt * maxclq,PetscInt *iwa1,PetscInt * iwa2,PetscInt * iwa3,PetscInt * iwa4) 8: {
9: /* System generated locals */
10: PetscInt i__1, i__2, i__3, i__4;
12: /* Local variables */
13: PetscInt jcol, ic, ip, jp, ir, mindeg, numdeg, numord;
15: /* Given the sparsity pattern of an m by n matrix A, this */
16: /* subroutine determines the smallest-last ordering of the */
17: /* columns of A. */
18: /* The smallest-last ordering is defined for the loopless */
19: /* graph G with vertices a(j), j = 1,2,...,n where a(j) is the */
20: /* j-th column of A and with edge (a(i),a(j)) if and only if */
21: /* columns i and j have a non-zero in the same row position. */
22: /* The smallest-last ordering is determined recursively by */
23: /* letting list(k), k = n,...,1 be a column with least degree */
24: /* in the subgraph spanned by the un-ordered columns. */
25: /* Note that the value of m is not needed by slo and is */
26: /* therefore not present in the subroutine statement. */
27: /* The subroutine statement is */
28: /* subroutine slo(n,indrow,jpntr,indcol,ipntr,ndeg,list, */
29: /* maxclq,iwa1,iwa2,iwa3,iwa4) */
30: /* where */
31: /* n is a positive integer input variable set to the number */
32: /* of columns of A. */
33: /* indrow is an integer input array which contains the row */
34: /* indices for the non-zeroes in the matrix A. */
35: /* jpntr is an integer input array of length n + 1 which */
36: /* specifies the locations of the row indices in indrow. */
37: /* The row indices for column j are */
38: /* indrow(k), k = jpntr(j),...,jpntr(j+1)-1. */
39: /* Note that jpntr(n+1)-1 is then the number of non-zero */
40: /* elements of the matrix A. */
41: /* indcol is an integer input array which contains the */
42: /* column indices for the non-zeroes in the matrix A. */
43: /* ipntr is an integer input array of length m + 1 which */
44: /* specifies the locations of the column indices in indcol. */
45: /* The column indices for row i are */
46: /* indcol(k), k = ipntr(i),...,ipntr(i+1)-1. */
47: /* Note that ipntr(m+1)-1 is then the number of non-zero */
48: /* elements of the matrix A. */
49: /* ndeg is an integer input array of length n which specifies */
50: /* the degree sequence. The degree of the j-th column */
51: /* of A is ndeg(j). */
52: /* list is an integer output array of length n which specifies */
53: /* the smallest-last ordering of the columns of A. The j-th */
54: /* column in this order is list(j). */
55: /* maxclq is an integer output variable set to the size */
56: /* of the largest clique found during the ordering. */
57: /* iwa1,iwa2,iwa3, and iwa4 are integer work arrays of length n. */
58: /* Subprograms called */
59: /* FORTRAN-supplied ... min */
60: /* Argonne National Laboratory. MINPACK Project. August 1984. */
61: /* Thomas F. Coleman, Burton S. Garbow, Jorge J. More' */
64: /* Parameter adjustments */
65: --iwa4;
66: --iwa3;
67: --iwa2;
68: --list;
69: --ndeg;
70: --ipntr;
71: --indcol;
72: --jpntr;
73: --indrow;
75: /* Function Body */
76: mindeg = *n;
77: i__1 = *n;
78: for (jp = 1; jp <= i__1; ++jp) {
79: iwa1[jp - 1] = 0;
80: iwa4[jp] = *n;
81: list[jp] = ndeg[jp];
82: /* Computing MIN */
83: i__2 = mindeg;
84: i__3 = ndeg[jp];
85: mindeg = PetscMin(i__2,i__3);
86: }
88: /* Create a doubly-linked list to access the degrees of the */
89: /* columns. The pointers for the linked list are as follows. */
91: /* Each un-ordered column ic is in a list (the degree list) */
92: /* of columns with the same degree. */
94: /* iwa1(numdeg) is the first column in the numdeg list */
95: /* unless iwa1(numdeg) = 0. In this case there are */
96: /* no columns in the numdeg list. */
98: /* iwa2(ic) is the column before ic in the degree list */
99: /* unless iwa2(ic) = 0. In this case ic is the first */
100: /* column in this degree list. */
102: /* iwa3(ic) is the column after ic in the degree list */
103: /* unless iwa3(ic) = 0. In this case ic is the last */
104: /* column in this degree list. */
106: /* If ic is an un-ordered column, then list(ic) is the */
107: /* degree of ic in the graph induced by the un-ordered */
108: /* columns. If jcol is an ordered column, then list(jcol) */
109: /* is the smallest-last order of column jcol. */
111: i__1 = *n;
112: for (jp = 1; jp <= i__1; ++jp) {
113: numdeg = ndeg[jp];
114: iwa2[jp] = 0;
115: iwa3[jp] = iwa1[numdeg];
116: if (iwa1[numdeg] > 0) {
117: iwa2[iwa1[numdeg]] = jp;
118: }
119: iwa1[numdeg] = jp;
120: }
121: *maxclq = 0;
122: numord = *n;
124: /* Beginning of iteration loop. */
126: L30:128: /* Choose a column jcol of minimal degree mindeg. */
130: L40:131: jcol = iwa1[mindeg];
132: if (jcol > 0) goto L50;
133: ++mindeg;
134: goto L40;
135: L50:136: list[jcol] = numord;
138: /* Mark the size of the largest clique */
139: /* found during the ordering. */
141: if (mindeg + 1 == numord && !*maxclq) *maxclq = numord;
143: /* Termination test. */
145: --numord;
146: if (!numord) goto L80;
148: /* Delete column jcol from the mindeg list. */
150: iwa1[mindeg] = iwa3[jcol];
151: if (iwa3[jcol] > 0) iwa2[iwa3[jcol]] = 0;
153: /* Find all columns adjacent to column jcol. */
155: iwa4[jcol] = 0;
157: /* Determine all positions (ir,jcol) which correspond */
158: /* to non-zeroes in the matrix. */
160: i__1 = jpntr[jcol + 1] - 1;
161: for (jp = jpntr[jcol]; jp <= i__1; ++jp) {
162: ir = indrow[jp];
164: /* For each row ir, determine all positions (ir,ic) */
165: /* which correspond to non-zeroes in the matrix. */
167: i__2 = ipntr[ir + 1] - 1;
168: for (ip = ipntr[ir]; ip <= i__2; ++ip) {
169: ic = indcol[ip];
171: /* Array iwa4 marks columns which are adjacent to */
172: /* column jcol. */
174: if (iwa4[ic] > numord) {
175: iwa4[ic] = numord;
177: /* Update the pointers to the current degree lists. */
179: numdeg = list[ic];
180: --list[ic];
181: /* Computing MIN */
182: i__3 = mindeg;
183: i__4 = list[ic];
184: mindeg = PetscMin(i__3,i__4);
186: /* Delete column ic from the numdeg list. */
188: if (!iwa2[ic]) iwa1[numdeg] = iwa3[ic];
189: else iwa3[iwa2[ic]] = iwa3[ic];
191: if (iwa3[ic] > 0) iwa2[iwa3[ic]] = iwa2[ic];
193: /* Add column ic to the numdeg-1 list. */
195: iwa2[ic] = 0;
196: iwa3[ic] = iwa1[numdeg - 1];
197: if (iwa1[numdeg - 1] > 0) iwa2[iwa1[numdeg - 1]] = ic;
198: iwa1[numdeg - 1] = ic;
199: }
200: }
201: }
203: /* End of iteration loop. */
205: goto L30;
206: L80:208: /* Invert the array list. */
210: i__1 = *n;
211: for (jcol = 1; jcol <= i__1; ++jcol) iwa2[list[jcol]] = jcol;
213: i__1 = *n;
214: for (jp = 1; jp <= i__1; ++jp) list[jp] = iwa2[jp];
215: return(0);
216: }