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: /*****************************************************************/
 37: PetscErrorCode SPARSEPACKqmdmrg(const PetscInt *xadj,const PetscInt *adjncy, PetscInt *deg,
 38:                                 PetscInt *qsize, PetscInt *qlink, PetscInt *marker, PetscInt *deg0,
 39:                                 PetscInt *nhdsze, PetscInt *nbrhd, PetscInt *rchset, PetscInt *ovrlp)
 40: {
 41:   /* System generated locals */
 42:   PetscInt i__1, i__2, i__3;

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

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

 60:   if (*nhdsze <= 0) return(0);
 61:   i__1 = *nhdsze;
 62:   for (inhd = 1; inhd <= i__1; ++inhd) {
 63:     root         = nbrhd[inhd];
 64:     marker[root] = 0;
 65:   }
 66: /*       LOOP THROUGH EACH ELIMINATED SUPERNODE IN THE SET     */
 67: /*       (NHDSZE, NBRHD).                                      */
 68:   i__1 = *nhdsze;
 69:   for (inhd = 1; inhd <= i__1; ++inhd) {
 70:     root         = nbrhd[inhd];
 71:     marker[root] = -1;
 72:     rchsze       = 0;
 73:     novrlp       = 0;
 74:     deg1         = 0;
 75: L200:
 76:     jstrt = xadj[root];
 77:     jstop = xadj[root + 1] - 1;
 78: /*          DETERMINE THE REACHABLE SET AND ITS PETSCINTERSECT-     */
 79: /*          ION WITH THE INPUT REACHABLE SET.                  */
 80:     i__2 = jstop;
 81:     for (j = jstrt; j <= i__2; ++j) {
 82:       nabor = adjncy[j];
 83:       root  = -nabor;
 84:       if (nabor < 0) goto L200;
 85:       else if (!nabor) goto L700;
 86:       else goto L300;
 87: L300:
 88:       mark = marker[nabor];
 89:       if (mark < 0) goto L600;
 90:       else if (!mark) goto L400;
 91:       else goto L500;
 92: L400:
 93:       ++rchsze;
 94:       rchset[rchsze] = nabor;
 95:       deg1          += qsize[nabor];
 96:       marker[nabor]  = 1;
 97:       goto L600;
 98: L500:
 99:       if (mark > 1) goto L600;
100:       ++novrlp;
101:       ovrlp[novrlp] = nabor;
102:       marker[nabor] = 2;
103: L600:
104:       ;
105:     }
106: /*          FROM THE OVERLAPPED SET, DETERMINE THE NODES        */
107: /*          THAT CAN BE MERGED TOGETHER.                        */
108: L700:
109:     head   = 0;
110:     mrgsze = 0;
111:     i__2   = novrlp;
112:     for (iov = 1; iov <= i__2; ++iov) {
113:       node  = ovrlp[iov];
114:       jstrt = xadj[node];
115:       jstop = xadj[node + 1] - 1;
116:       i__3  = jstop;
117:       for (j = jstrt; j <= i__3; ++j) {
118:         nabor = adjncy[j];
119:         if (marker[nabor] != 0) goto L800;
120:         marker[node] = 1;
121:         goto L1100;
122: L800:
123:         ;
124:       }
125: /*             NODE BELONGS TO THE NEW MERGED SUPERNODE.      */
126: /*             UPDATE THE VECTORS QLINK AND QSIZE.            */
127:       mrgsze      += qsize[node];
128:       marker[node] = -1;
129:       lnode        = node;
130: L900:
131:       ilink = qlink[lnode];
132:       if (ilink <= 0) goto L1000;
133:       lnode = ilink;
134:       goto L900;
135: L1000:
136:       qlink[lnode] = head;
137:       head         = node;
138: L1100:
139:       ;
140:     }
141:     if (head <= 0) goto L1200;
142:     qsize[head]  = mrgsze;
143:     deg[head]    = *deg0 + deg1 - 1;
144:     marker[head] = 2;
145: /*          RESET MARKER VALUES.          */
146: L1200:
147:     root         = nbrhd[inhd];
148:     marker[root] = 0;
149:     if (rchsze <= 0) goto L1400;
150:     i__2 = rchsze;
151:     for (irch = 1; irch <= i__2; ++irch) {
152:       node         = rchset[irch];
153:       marker[node] = 0;
154:     }
155: L1400:
156:     ;
157:   }
158:   return(0);
159: }