Actual source code: qmdmrg.c


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

  4: #include <petscsys.h>
  5: #include <petsc/private/matorderimpl.h>

  7: /******************************************************************/
  8: /***********     QMDMRG ..... QUOT MIN DEG MERGE       ************/
  9: /******************************************************************/
 10: /*    PURPOSE - THIS ROUTINE MERGES INDISTINGUISHABLE NODES IN   */
 11: /*              THE MINIMUM DEGREE ORDERING ALGORITHM.           */
 12: /*              IT ALSO COMPUTES THE NEW DEGREES OF THESE        */
 13: /*              NEW SUPERNODES.                                  */
 14: /*                                                               */
 15: /*    INPUT PARAMETERS -                                         */
 16: /*       (XADJ, ADJNCY) - THE ADJACENCY STRUCTURE.               */
 17: /*       DEG0 - THE NUMBER OF NODES IN THE GIVEN SET.            */
 18: /*       (NHDSZE, NBRHD) - THE SET OF ELIMINATED SUPERNODES      */
 19: /*              ADJACENT TO SOME NODES IN THE SET.               */
 20: /*                                                               */
 21: /*    UPDATED PARAMETERS -                                       */
 22: /*       DEG - THE DEGREE VECTOR.                                */
 23: /*       QSIZE - SIZE OF INDISTINGUISHABLE NODES.                */
 24: /*       QLINK - LINKED LIST FOR INDISTINGUISHABLE NODES.        */
 25: /*       MARKER - THE GIVEN SET IS GIVEN BY THOSE NODES WITH     */
 26: /*              MARKER VALUE SET TO 1.  THOSE NODES WITH DEGREE  */
 27: /*              UPDATED WILL HAVE MARKER VALUE SET TO 2.         */
 28: /*                                                               */
 29: /*    WORKING PARAMETERS -                                       */
 30: /*       RCHSET - THE REACHABLE SET.                             */
 31: /*       OVRLP -  TEMP VECTOR TO STORE THE INTERSECTION OF TWO   */
 32: /*              REACHABLE SETS.                                  */
 33: /*                                                               */
 34: /*****************************************************************/
 35: PetscErrorCode SPARSEPACKqmdmrg(const PetscInt *xadj, const PetscInt *adjncy, PetscInt *deg, PetscInt *qsize, PetscInt *qlink, PetscInt *marker, PetscInt *deg0, PetscInt *nhdsze, PetscInt *nbrhd, PetscInt *rchset, PetscInt *ovrlp)
 36: {
 37:   /* System generated locals */
 38:   PetscInt i__1, i__2, i__3;

 40:   /* Local variables */
 41:   PetscInt head, inhd, irch, node, mark, ilink, root, j, lnode, nabor, jstop, jstrt, rchsze, mrgsze, novrlp, iov, deg1;

 43:   /* Parameter adjustments */
 44:   --ovrlp;
 45:   --rchset;
 46:   --nbrhd;
 47:   --marker;
 48:   --qlink;
 49:   --qsize;
 50:   --deg;
 51:   --adjncy;
 52:   --xadj;

 54:   if (*nhdsze <= 0) return 0;
 55:   i__1 = *nhdsze;
 56:   for (inhd = 1; inhd <= i__1; ++inhd) {
 57:     root         = nbrhd[inhd];
 58:     marker[root] = 0;
 59:   }
 60:   /*       LOOP THROUGH EACH ELIMINATED SUPERNODE IN THE SET     */
 61:   /*       (NHDSZE, NBRHD).                                      */
 62:   i__1 = *nhdsze;
 63:   for (inhd = 1; inhd <= i__1; ++inhd) {
 64:     root         = nbrhd[inhd];
 65:     marker[root] = -1;
 66:     rchsze       = 0;
 67:     novrlp       = 0;
 68:     deg1         = 0;
 69:   L200:
 70:     jstrt = xadj[root];
 71:     jstop = xadj[root + 1] - 1;
 72:     /*          DETERMINE THE REACHABLE SET AND ITS PETSCINTERSECT-     */
 73:     /*          ION WITH THE INPUT REACHABLE SET.                  */
 74:     i__2 = jstop;
 75:     for (j = jstrt; j <= i__2; ++j) {
 76:       nabor = adjncy[j];
 77:       root  = -nabor;
 78:       if (nabor < 0) goto L200;
 79:       else if (!nabor) goto L700;
 80:       else goto L300;
 81:     L300:
 82:       mark = marker[nabor];
 83:       if (mark < 0) goto L600;
 84:       else if (!mark) goto L400;
 85:       else goto L500;
 86:     L400:
 87:       ++rchsze;
 88:       rchset[rchsze] = nabor;
 89:       deg1 += qsize[nabor];
 90:       marker[nabor] = 1;
 91:       goto L600;
 92:     L500:
 93:       if (mark > 1) goto L600;
 94:       ++novrlp;
 95:       ovrlp[novrlp] = nabor;
 96:       marker[nabor] = 2;
 97:     L600:;
 98:     }
 99:   /*          FROM THE OVERLAPPED SET, DETERMINE THE NODES        */
100:   /*          THAT CAN BE MERGED TOGETHER.                        */
101:   L700:
102:     head   = 0;
103:     mrgsze = 0;
104:     i__2   = novrlp;
105:     for (iov = 1; iov <= i__2; ++iov) {
106:       node  = ovrlp[iov];
107:       jstrt = xadj[node];
108:       jstop = xadj[node + 1] - 1;
109:       i__3  = jstop;
110:       for (j = jstrt; j <= i__3; ++j) {
111:         nabor = adjncy[j];
112:         if (marker[nabor] != 0) goto L800;
113:         marker[node] = 1;
114:         goto L1100;
115:       L800:;
116:       }
117:       /*             NODE BELONGS TO THE NEW MERGED SUPERNODE.      */
118:       /*             UPDATE THE VECTORS QLINK AND QSIZE.            */
119:       mrgsze += qsize[node];
120:       marker[node] = -1;
121:       lnode        = node;
122:     L900:
123:       ilink = qlink[lnode];
124:       if (ilink <= 0) goto L1000;
125:       lnode = ilink;
126:       goto L900;
127:     L1000:
128:       qlink[lnode] = head;
129:       head         = node;
130:     L1100:;
131:     }
132:     if (head <= 0) goto L1200;
133:     qsize[head]  = mrgsze;
134:     deg[head]    = *deg0 + deg1 - 1;
135:     marker[head] = 2;
136:   /*          RESET MARKER VALUES.          */
137:   L1200:
138:     root         = nbrhd[inhd];
139:     marker[root] = 0;
140:     if (rchsze <= 0) goto L1400;
141:     i__2 = rchsze;
142:     for (irch = 1; irch <= i__2; ++irch) {
143:       node         = rchset[irch];
144:       marker[node] = 0;
145:     }
146:   L1400:;
147:   }
148:   return 0;
149: }