1 /* seq.f -- translated by f2c (version of 25 March 1992 12:58:56). */
2
3 #include <../src/mat/graphops/color/impls/minpack/color.h>
4
MINPACKseq(PetscInt * n,const PetscInt * indrow,const PetscInt * jpntr,const PetscInt * indcol,const PetscInt * ipntr,PetscInt * list,PetscInt * ngrp,PetscInt * maxgrp,PetscInt * iwa)5 PetscErrorCode MINPACKseq(PetscInt *n, const PetscInt *indrow, const PetscInt *jpntr, const PetscInt *indcol, const PetscInt *ipntr, PetscInt *list, PetscInt *ngrp, PetscInt *maxgrp, PetscInt *iwa)
6 {
7 /* System generated locals */
8 PetscInt i__1, i__2, i__3;
9
10 /* Local variables */
11 PetscInt jcol, j, ic, ip, jp, ir;
12
13 /* Given the sparsity pattern of an m by n matrix A, this */
14 /* subroutine determines a consistent partition of the */
15 /* columns of A by a sequential algorithm. */
16 /* A consistent partition is defined in terms of the loopless */
17 /* graph G with vertices a(j), j = 1,2,...,n where a(j) is the */
18 /* j-th column of A and with edge (a(i),a(j)) if and only if */
19 /* columns i and j have a non-zero in the same row position. */
20 /* A partition of the columns of A into groups is consistent */
21 /* if the columns in any group are not adjacent in the graph G. */
22 /* In graph-theory terminology, a consistent partition of the */
23 /* columns of A corresponds to a coloring of the graph G. */
24 /* The subroutine examines the columns in the order specified */
25 /* by the array list, and assigns the current column to the */
26 /* group with the smallest possible number. */
27 /* Note that the value of m is not needed by seq and is */
28 /* therefore not present in the subroutine statement. */
29 /* The subroutine statement is */
30 /* subroutine seq(n,indrow,jpntr,indcol,ipntr,list,ngrp,maxgrp, */
31 /* iwa) */
32 /* where */
33 /* n is a positive integer input variable set to the number */
34 /* of columns of A. */
35 /* indrow is an integer input array which contains the row */
36 /* indices for the non-zeroes in the matrix A. */
37 /* jpntr is an integer input array of length n + 1 which */
38 /* specifies the locations of the row indices in indrow. */
39 /* The row indices for column j are */
40 /* indrow(k), k = jpntr(j),...,jpntr(j+1)-1. */
41 /* Note that jpntr(n+1)-1 is then the number of non-zero */
42 /* elements of the matrix A. */
43 /* indcol is an integer input array which contains the */
44 /* column indices for the non-zeroes in the matrix A. */
45 /* ipntr is an integer input array of length m + 1 which */
46 /* specifies the locations of the column indices in indcol. */
47 /* The column indices for row i are */
48 /* indcol(k), k = ipntr(i),...,ipntr(i+1)-1. */
49 /* Note that ipntr(m+1)-1 is then the number of non-zero */
50 /* elements of the matrix A. */
51 /* list is an integer input array of length n which specifies */
52 /* the order to be used by the sequential algorithm. */
53 /* The j-th column in this order is list(j). */
54 /* ngrp is an integer output array of length n which specifies */
55 /* the partition of the columns of A. Column jcol belongs */
56 /* to group ngrp(jcol). */
57 /* maxgrp is an integer output variable which specifies the */
58 /* number of groups in the partition of the columns of A. */
59 /* iwa is an integer work array of length n. */
60 /* Argonne National Laboratory. MINPACK Project. July 1983. */
61 /* Thomas F. Coleman, Burton S. Garbow, Jorge J. More' */
62
63 PetscFunctionBegin;
64 /* Parameter adjustments */
65 --iwa;
66 --ngrp;
67 --list;
68 --ipntr;
69 --indcol;
70 --jpntr;
71 --indrow;
72
73 /* Function Body */
74 *maxgrp = 0;
75 i__1 = *n;
76 for (jp = 1; jp <= i__1; ++jp) {
77 ngrp[jp] = *n;
78 iwa[jp] = 0;
79 }
80
81 /* Beginning of iteration loop. */
82
83 i__1 = *n;
84 for (j = 1; j <= i__1; ++j) {
85 jcol = list[j];
86
87 /* Find all columns adjacent to column jcol. */
88
89 /* Determine all positions (ir,jcol) which correspond */
90 /* to non-zeroes in the matrix. */
91
92 i__2 = jpntr[jcol + 1] - 1;
93 for (jp = jpntr[jcol]; jp <= i__2; ++jp) {
94 ir = indrow[jp];
95
96 /* For each row ir, determine all positions (ir,ic) */
97 /* which correspond to non-zeroes in the matrix. */
98
99 i__3 = ipntr[ir + 1] - 1;
100 for (ip = ipntr[ir]; ip <= i__3; ++ip) {
101 ic = indcol[ip];
102
103 /* Array iwa marks the group numbers of the */
104 /* columns which are adjacent to column jcol. */
105
106 iwa[ngrp[ic]] = j;
107 }
108 }
109
110 /* Assign the smallest un-marked group number to jcol. */
111
112 i__2 = *maxgrp;
113 for (jp = 1; jp <= i__2; ++jp) {
114 if (iwa[jp] != j) goto L50;
115 }
116 ++(*maxgrp);
117 L50:
118 ngrp[jcol] = jp;
119 }
120
121 /* End of iteration loop. */
122 PetscFunctionReturn(PETSC_SUCCESS);
123 }
124