Actual source code: rcm.c

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

 3:  #include petsc.h

  5: /*****************************************************************/
  6: /*********     RCM ..... REVERSE CUTHILL-MCKEE ORDERING   *******/
  7: /*****************************************************************/
  8: /*    PURPOSE - RCM NUMBERS A CONNECTED COMPONENT SPECIFIED BY    */
  9: /*       MASK AND ../../.., USING THE RCM ALGORITHM.                  */
 10: /*       THE NUMBERING IS TO BE STARTED AT THE NODE ../../...         */
 11: /*                                                               */
 12: /*    INPUT PARAMETERS -                                         */
 13: /*       ../../.. - IS THE NODE THAT DEFINES THE CONNECTED           */
 14: /*              COMPONENT AND IT IS USED AS THE STARTING         */
 15: /*              NODE FOR THE RCM ORDERING.                       */
 16: /*       (XADJ, ADJNCY) - ADJACENCY STRUCTURE PAIR FOR           */
 17: /*              THE GRAPH.                                       */
 18: /*                                                               */
 19: /*    UPDATED PARAMETERS -                                       */
 20: /*       MASK - ONLY THOSE NODES WITH NONZERO INPUT MASK         */
 21: /*              VALUES ARE CONSIDERED BY THE ROUTINE.  THE       */
 22: /*              NODES NUMBERED BY RCM WILL HAVE THEIR            */
 23: /*              MASK VALUES SET TO ZERO.                         */
 24: /*                                                               */
 25: /*    OUTPUT PARAMETERS -                                        */
 26: /*       PERM - WILL CONTAIN THE RCM ORDERING.                   */
 27: /*       CCSIZE - IS THE SIZE OF THE CONNECTED COMPONENT         */
 28: /*              THAT HAS BEEN NUMBERED BY RCM.                  */
 29: /*                                                              */
 30: /*    WORKING PARAMETER -                                       */
 31: /*       DEG - IS A TEMPORARY VECTOR USED TO HOLD THE DEGREE    */
 32: /*              OF THE NODES IN THE SECTION GRAPH SPECIFIED     */
 33: /*              BY MASK AND ../../...                               */
 34: /*                                                              */
 35: /*    PROGRAM SUBROUTINES -                                     */
 36: /*       DEGREE.                                                */
 37: /*                                                              */
 38: /****************************************************************/
 41: PetscErrorCode SPARSEPACKrcm(PetscInt *root, PetscInt *xadj, PetscInt *adjncy, 
 42:         PetscInt *mask, PetscInt *perm, PetscInt *ccsize, PetscInt *deg)
 43: {
 44:     /* System generated locals */
 45:     PetscInt i__1, i__2;

 47:     /* Local variables */
 48:     PetscInt node, fnbr, lnbr, i, j, k, l, lperm, jstop, jstrt;
 49:     EXTERN PetscErrorCode SPARSEPACKdegree(PetscInt*, PetscInt *, PetscInt *,
 50:             PetscInt *, PetscInt *, PetscInt *, PetscInt *);
 51:     PetscInt lbegin, lvlend, nbr;

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


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


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

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