Actual source code: rcm.c
petsc-3.6.1 2015-08-06
2: /* rcm.f -- translated by f2c (version 19931217).*/
4: #include <petscsys.h>
5: #include <petsc/private/matorderimpl.h>
7: /*****************************************************************/
8: /********* RCM ..... REVERSE CUTHILL-MCKEE ORDERING *******/
9: /*****************************************************************/
10: /* PURPOSE - RCM NUMBERS A CONNECTED COMPONENT SPECIFIED BY */
11: /* MASK AND ../../.., USING THE RCM ALGORITHM. */
12: /* THE NUMBERING IS TO BE STARTED AT THE NODE ../../... */
13: /* */
14: /* INPUT PARAMETERS - */
15: /* ../../.. - IS THE NODE THAT DEFINES THE CONNECTED */
16: /* COMPONENT AND IT IS USED AS THE STARTING */
17: /* NODE FOR THE RCM ORDERING. */
18: /* (XADJ, ADJNCY) - ADJACENCY STRUCTURE PAIR FOR */
19: /* THE GRAPH. */
20: /* */
21: /* UPDATED PARAMETERS - */
22: /* MASK - ONLY THOSE NODES WITH NONZERO INPUT MASK */
23: /* VALUES ARE CONSIDERED BY THE ROUTINE. THE */
24: /* NODES NUMBERED BY RCM WILL HAVE THEIR */
25: /* MASK VALUES SET TO ZERO. */
26: /* */
27: /* OUTPUT PARAMETERS - */
28: /* PERM - WILL CONTAIN THE RCM ORDERING. */
29: /* CCSIZE - IS THE SIZE OF THE CONNECTED COMPONENT */
30: /* THAT HAS BEEN NUMBERED BY RCM. */
31: /* */
32: /* WORKING PARAMETER - */
33: /* DEG - IS A TEMPORARY VECTOR USED TO HOLD THE DEGREE */
34: /* OF THE NODES IN THE SECTION GRAPH SPECIFIED */
35: /* BY MASK AND ../../... */
36: /* */
37: /* PROGRAM SUBROUTINES - */
38: /* DEGREE. */
39: /* */
40: /****************************************************************/
43: PetscErrorCode SPARSEPACKrcm(const PetscInt *root,const PetscInt *xadj,const PetscInt *adjncy,PetscInt *mask, PetscInt *perm, PetscInt *ccsize, PetscInt *deg)
44: {
45: /* System generated locals */
46: PetscInt i__1, i__2;
48: /* Local variables */
49: PetscInt node, fnbr, lnbr, i, j, k, l, lperm, jstop, jstrt;
50: PetscInt lbegin, lvlend, nbr;
52: /* FIND THE DEGREES OF THE NODES IN THE */
53: /* COMPONENT SPECIFIED BY MASK AND ../../... */
54: /* ------------------------------------- */
58: /* Parameter adjustments */
59: --deg;
60: --perm;
61: --mask;
62: --adjncy;
63: --xadj;
66: SPARSEPACKdegree(root, &xadj[1], &adjncy[1], &mask[1], °[1], ccsize, &perm[1]);
67: mask[*root] = 0;
68: if (*ccsize <= 1) return(0);
69: lvlend = 0;
70: lnbr = 1;
71: /* LBEGIN AND LVLEND POINT TO THE BEGINNING AND */
72: /* THE END OF THE CURRENT LEVEL RESPECTIVELY. */
73: L100:
74: lbegin = lvlend + 1;
75: lvlend = lnbr;
76: i__1 = lvlend;
77: for (i = lbegin; i <= i__1; ++i) {
78: /* FOR EACH NODE IN CURRENT LEVEL ... */
79: node = perm[i];
80: jstrt = xadj[node];
81: jstop = xadj[node + 1] - 1;
83: /* FIND THE UNNUMBERED NEIGHBORS OF NODE. */
84: /* FNBR AND LNBR POINT TO THE FIRST AND LAST */
85: /* UNNUMBERED NEIGHBORS RESPECTIVELY OF THE CURRENT */
86: /* NODE IN PERM. */
87: fnbr = lnbr + 1;
88: i__2 = jstop;
89: for (j = jstrt; j <= i__2; ++j) {
90: nbr = adjncy[j];
91: if (!mask[nbr]) goto L200;
92: ++lnbr;
93: mask[nbr] = 0;
94: perm[lnbr] = nbr;
95: L200:
96: ;
97: }
98: if (fnbr >= lnbr) goto L600;
100: /* SORT THE NEIGHBORS OF NODE IN INCREASING */
101: /* ORDER BY DEGREE. LINEAR INSERTION IS USED.*/
102: k = fnbr;
103: L300:
104: l = k;
105: ++k;
106: nbr = perm[k];
107: L400:
108: if (l < fnbr) goto L500;
109: lperm = perm[l];
110: if (deg[lperm] <= deg[nbr]) goto L500;
111: perm[l + 1] = lperm;
112: --l;
113: goto L400;
114: L500:
115: perm[l + 1] = nbr;
116: if (k < lnbr) goto L300;
117: L600:
118: ;
119: }
120: if (lnbr > lvlend) goto L100;
122: /* WE NOW HAVE THE CUTHILL MCKEE ORDERING.*/
123: /* REVERSE IT BELOW ...*/
124: k = *ccsize / 2;
125: l = *ccsize;
126: i__1 = k;
127: for (i = 1; i <= i__1; ++i) {
128: lperm = perm[l];
129: perm[l] = perm[i];
130: perm[i] = lperm;
131: --l;
132: }
133: return(0);
134: }