2: /* degr.f -- translated by f2c (version of 25 March 1992 12:58:56). */
4: #include <../src/mat/color/color.h>
8: PetscErrorCode MINPACKdegr(PetscInt *n,PetscInt * indrow,PetscInt * jpntr,PetscInt * indcol,PetscInt * ipntr,PetscInt * ndeg,PetscInt * iwa) 9: {
10: /* System generated locals */
11: PetscInt i__1, i__2, i__3;
13: /* Local variables */
14: PetscInt jcol, ic, ip, jp, ir;
16: /* subroutine degr */
17: /* Given the sparsity pattern of an m by n matrix A, */
18: /* this subroutine determines the degree sequence for */
19: /* the intersection graph of the columns of A. */
20: /* In graph-theory terminology, the intersection graph of */
21: /* the columns of A is the loopless graph G with vertices */
22: /* a(j), j = 1,2,...,n where a(j) is the j-th column of A */
23: /* and with edge (a(i),a(j)) if and only if columns i and j */
24: /* have a non-zero in the same row position. */
25: /* Note that the value of m is not needed by degr and is */
26: /* therefore not present in the subroutine statement. */
27: /* The subroutine statement is */
28: /* subroutine degr(n,indrow,jpntr,indcol,ipntr,ndeg,iwa) */
29: /* where */
30: /* n is a positive integer input variable set to the number */
31: /* of columns of A. */
32: /* indrow is an integer input array which contains the row */
33: /* indices for the non-zeroes in the matrix A. */
34: /* jpntr is an integer input array of length n + 1 which */
35: /* specifies the locations of the row indices in indrow. */
36: /* The row indices for column j are */
37: /* indrow(k), k = jpntr(j),...,jpntr(j+1)-1. */
38: /* Note that jpntr(n+1)-1 is then the number of non-zero */
39: /* elements of the matrix A. */
40: /* indcol is an integer input array which contains the */
41: /* column indices for the non-zeroes in the matrix A. */
42: /* ipntr is an integer input array of length m + 1 which */
43: /* specifies the locations of the column indices in indcol. */
44: /* The column indices for row i are */
45: /* indcol(k), k = ipntr(i),...,ipntr(i+1)-1. */
46: /* Note that ipntr(m+1)-1 is then the number of non-zero */
47: /* elements of the matrix A. */
48: /* ndeg is an integer output array of length n which */
49: /* specifies the degree sequence. The degree of the */
50: /* j-th column of A is ndeg(j). */
51: /* iwa is an integer work array of length n. */
52: /* Argonne National Laboratory. MINPACK Project. July 1983. */
53: /* Thomas F. Coleman, Burton S. Garbow, Jorge J. More' */
56: /* Parameter adjustments */
57: --iwa;
58: --ndeg;
59: --ipntr;
60: --indcol;
61: --jpntr;
62: --indrow;
64: /* Function Body */
65: i__1 = *n;
66: for (jp = 1; jp <= i__1; ++jp) {
67: ndeg[jp] = 0;
68: iwa[jp] = 0;
69: }
71: /* Compute the degree sequence by determining the contributions */
72: /* to the degrees from the current(jcol) column and further */
73: /* columns which have not yet been considered. */
75: i__1 = *n;
76: for (jcol = 2; jcol <= i__1; ++jcol) {
77: iwa[jcol] = *n;
79: /* Determine all positions (ir,jcol) which correspond */
80: /* to non-zeroes in the matrix. */
82: i__2 = jpntr[jcol + 1] - 1;
83: for (jp = jpntr[jcol]; jp <= i__2; ++jp) {
84: ir = indrow[jp];
86: /* For each row ir, determine all positions (ir,ic) */
87: /* which correspond to non-zeroes in the matrix. */
89: i__3 = ipntr[ir + 1] - 1;
90: for (ip = ipntr[ir]; ip <= i__3; ++ip) {
91: ic = indcol[ip];
93: /* Array iwa marks columns which have contributed to */
94: /* the degree count of column jcol. Update the degree */
95: /* counts of these columns as well as column jcol. */
97: if (iwa[ic] < jcol) {
98: iwa[ic] = jcol;
99: ++ndeg[ic];
100: ++ndeg[jcol];
101: }
102: }
103: }
104: }
105: return(0);
106: }