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,
 36:                                 PetscInt *qsize, PetscInt *qlink, PetscInt *marker, PetscInt *deg0,
 37:                                 PetscInt *nhdsze, PetscInt *nbrhd, PetscInt *rchset, PetscInt *ovrlp)
 38: {
 39:   /* System generated locals */
 40:   PetscInt i__1, i__2, i__3;

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

 47:   /* Parameter adjustments */
 48:   --ovrlp;
 49:   --rchset;
 50:   --nbrhd;
 51:   --marker;
 52:   --qlink;
 53:   --qsize;
 54:   --deg;
 55:   --adjncy;
 56:   --xadj;

 58:   if (*nhdsze <= 0) return(0);
 59:   i__1 = *nhdsze;
 60:   for (inhd = 1; inhd <= i__1; ++inhd) {
 61:     root         = nbrhd[inhd];
 62:     marker[root] = 0;
 63:   }
 64: /*       LOOP THROUGH EACH ELIMINATED SUPERNODE IN THE SET     */
 65: /*       (NHDSZE, NBRHD).                                      */
 66:   i__1 = *nhdsze;
 67:   for (inhd = 1; inhd <= i__1; ++inhd) {
 68:     root         = nbrhd[inhd];
 69:     marker[root] = -1;
 70:     rchsze       = 0;
 71:     novrlp       = 0;
 72:     deg1         = 0;
 73: L200:
 74:     jstrt = xadj[root];
 75:     jstop = xadj[root + 1] - 1;
 76: /*          DETERMINE THE REACHABLE SET AND ITS PETSCINTERSECT-     */
 77: /*          ION WITH THE INPUT REACHABLE SET.                  */
 78:     i__2 = jstop;
 79:     for (j = jstrt; j <= i__2; ++j) {
 80:       nabor = adjncy[j];
 81:       root  = -nabor;
 82:       if (nabor < 0) goto L200;
 83:       else if (!nabor) goto L700;
 84:       else goto L300;
 85: L300:
 86:       mark = marker[nabor];
 87:       if (mark < 0) goto L600;
 88:       else if (!mark) goto L400;
 89:       else goto L500;
 90: L400:
 91:       ++rchsze;
 92:       rchset[rchsze] = nabor;
 93:       deg1          += qsize[nabor];
 94:       marker[nabor]  = 1;
 95:       goto L600;
 96: L500:
 97:       if (mark > 1) goto L600;
 98:       ++novrlp;
 99:       ovrlp[novrlp] = nabor;
100:       marker[nabor] = 2;
101: L600:
102:       ;
103:     }
104: /*          FROM THE OVERLAPPED SET, DETERMINE THE NODES        */
105: /*          THAT CAN BE MERGED TOGETHER.                        */
106: L700:
107:     head   = 0;
108:     mrgsze = 0;
109:     i__2   = novrlp;
110:     for (iov = 1; iov <= i__2; ++iov) {
111:       node  = ovrlp[iov];
112:       jstrt = xadj[node];
113:       jstop = xadj[node + 1] - 1;
114:       i__3  = jstop;
115:       for (j = jstrt; j <= i__3; ++j) {
116:         nabor = adjncy[j];
117:         if (marker[nabor] != 0) goto L800;
118:         marker[node] = 1;
119:         goto L1100;
120: L800:
121:         ;
122:       }
123: /*             NODE BELONGS TO THE NEW MERGED SUPERNODE.      */
124: /*             UPDATE THE VECTORS QLINK AND QSIZE.            */
125:       mrgsze      += qsize[node];
126:       marker[node] = -1;
127:       lnode        = node;
128: L900:
129:       ilink = qlink[lnode];
130:       if (ilink <= 0) goto L1000;
131:       lnode = ilink;
132:       goto L900;
133: L1000:
134:       qlink[lnode] = head;
135:       head         = node;
136: L1100:
137:       ;
138:     }
139:     if (head <= 0) goto L1200;
140:     qsize[head]  = mrgsze;
141:     deg[head]    = *deg0 + deg1 - 1;
142:     marker[head] = 2;
143: /*          RESET MARKER VALUES.          */
144: L1200:
145:     root         = nbrhd[inhd];
146:     marker[root] = 0;
147:     if (rchsze <= 0) goto L1400;
148:     i__2 = rchsze;
149:     for (irch = 1; irch <= i__2; ++irch) {
150:       node         = rchset[irch];
151:       marker[node] = 0;
152:     }
153: L1400:
154:     ;
155:   }
156:   return(0);
157: }