Actual source code: rcm.c

  2: /* rcm.f -- translated by f2c (version 19931217).*/

  4: #include <petscsys.h>

  6: /*****************************************************************/
  7: /*********     RCM ..... REVERSE CUTHILL-MCKEE ORDERING   *******/
  8: /*****************************************************************/
  9: /*    PURPOSE - RCM NUMBERS A CONNECTED COMPONENT SPECIFIED BY    */
 10: /*       MASK AND ../../.., USING THE RCM ALGORITHM.                  */
 11: /*       THE NUMBERING IS TO BE STARTED AT THE NODE ../../...         */
 12: /*                                                               */
 13: /*    INPUT PARAMETERS -                                         */
 14: /*       ../../.. - IS THE NODE THAT DEFINES THE CONNECTED           */
 15: /*              COMPONENT AND IT IS USED AS THE STARTING         */
 16: /*              NODE FOR THE RCM ORDERING.                       */
 17: /*       (XADJ, ADJNCY) - ADJACENCY STRUCTURE PAIR FOR           */
 18: /*              THE GRAPH.                                       */
 19: /*                                                               */
 20: /*    UPDATED PARAMETERS -                                       */
 21: /*       MASK - ONLY THOSE NODES WITH NONZERO INPUT MASK         */
 22: /*              VALUES ARE CONSIDERED BY THE ROUTINE.  THE       */
 23: /*              NODES NUMBERED BY RCM WILL HAVE THEIR            */
 24: /*              MASK VALUES SET TO ZERO.                         */
 25: /*                                                               */
 26: /*    OUTPUT PARAMETERS -                                        */
 27: /*       PERM - WILL CONTAIN THE RCM ORDERING.                   */
 28: /*       CCSIZE - IS THE SIZE OF THE CONNECTED COMPONENT         */
 29: /*              THAT HAS BEEN NUMBERED BY RCM.                  */
 30: /*                                                              */
 31: /*    WORKING PARAMETER -                                       */
 32: /*       DEG - IS A TEMPORARY VECTOR USED TO HOLD THE DEGREE    */
 33: /*              OF THE NODES IN THE SECTION GRAPH SPECIFIED     */
 34: /*              BY MASK AND ../../...                               */
 35: /*                                                              */
 36: /*    PROGRAM SUBROUTINES -                                     */
 37: /*       DEGREE.                                                */
 38: /*                                                              */
 39: /****************************************************************/
 42: PetscErrorCode SPARSEPACKrcm(PetscInt *root, PetscInt *xadj, PetscInt *adjncy, 
 43:         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;
 51:             PetscInt *, PetscInt *, PetscInt *, PetscInt *);
 52:     PetscInt lbegin, lvlend, nbr;

 54: /*       FIND THE DEGREES OF THE NODES IN THE                  */
 55: /*       COMPONENT SPECIFIED BY MASK AND ../../...                 */
 56: /*       -------------------------------------                 */


 60:     /* Parameter adjustments */
 61:     --deg;
 62:     --perm;
 63:     --mask;
 64:     --adjncy;
 65:     --xadj;


 68:     SPARSEPACKdegree(root, &xadj[1], &adjncy[1], &mask[1], &deg[1], ccsize, &perm[1]);
 69:     mask[*root] = 0;
 70:     if (*ccsize <= 1) {
 71:         return(0);
 72:     }
 73:     lvlend = 0;
 74:     lnbr = 1;
 75: /*       LBEGIN AND LVLEND POINT TO THE BEGINNING AND */
 76: /*       THE END OF THE CURRENT LEVEL RESPECTIVELY.  */
 77: L100:
 78:     lbegin = lvlend + 1;
 79:     lvlend = lnbr;
 80:     i__1 = lvlend;
 81:     for (i = lbegin; i <= i__1; ++i) {
 82: /*          FOR EACH NODE IN CURRENT LEVEL ...     */
 83:         node = perm[i];
 84:         jstrt = xadj[node];
 85:         jstop = xadj[node + 1] - 1;

 87: /*          FIND THE UNNUMBERED NEIGHBORS OF NODE.   */
 88: /*          FNBR AND LNBR POINT TO THE FIRST AND LAST  */
 89: /*          UNNUMBERED NEIGHBORS RESPECTIVELY OF THE CURRENT  */
 90: /*          NODE IN PERM. */
 91:         fnbr = lnbr + 1;
 92:         i__2 = jstop;
 93:         for (j = jstrt; j <= i__2; ++j) {
 94:             nbr = adjncy[j];
 95:             if (!mask[nbr]) {
 96:                 goto L200;
 97:             }
 98:             ++lnbr;
 99:             mask[nbr] = 0;
100:             perm[lnbr] = nbr;
101: L200:
102:             ;
103:         }
104:         if (fnbr >= lnbr) {
105:             goto L600;
106:         }
107: /*             SORT THE NEIGHBORS OF NODE IN INCREASING    */
108: /*             ORDER BY DEGREE. LINEAR INSERTION IS USED.*/
109:         k = fnbr;
110: L300:
111:         l = k;
112:         ++k;
113:         nbr = perm[k];
114: L400:
115:         if (l < fnbr) {
116:             goto L500;
117:         }
118:         lperm = perm[l];
119:         if (deg[lperm] <= deg[nbr]) {
120:             goto L500;
121:         }
122:         perm[l + 1] = lperm;
123:         --l;
124:         goto L400;
125: L500:
126:         perm[l + 1] = nbr;
127:         if (k < lnbr) {
128:             goto L300;
129:         }
130: L600:
131:         ;
132:     }
133:     if (lnbr > lvlend) {
134:         goto L100;
135:     }
136: /*       WE NOW HAVE THE CUTHILL MCKEE ORDERING.*/
137: /*       REVERSE IT BELOW ...*/
138:     k = *ccsize / 2;
139:     l = *ccsize;
140:     i__1 = k;
141:     for (i = 1; i <= i__1; ++i) {
142:         lperm = perm[l];
143:         perm[l] = perm[i];
144:         perm[i] = lperm;
145:         --l;
146:     }
147:     return(0);
148: }