Date: 2021-03-03T22:26:43+00:00

Actual source code: gennd.c
petsc-3.14.5 2021-03-03
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      2: /* gennd.f -- translated by f2c (version 19931217).*/

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

      7: PetscErrorCode SPARSEPACKrevrse(const PetscInt *n,PetscInt *perm)
      8: {
      9:   /* System generated locals */
     10:   PetscInt i__1;

     12:   /* Local variables */
     13:   PetscInt swap,i,m,in;

     16:   /* Parameter adjustments */
     17:   --perm;

     19:   in   = *n;
     20:   m    = *n / 2;
     21:   i__1 = m;
     22:   for (i = 1; i <= i__1; ++i) {
     23:     swap     = perm[i];
     24:     perm[i]  = perm[in];
     25:     perm[in] = swap;
     26:     --in;
     27:   }
     28:   return(0);
     29: }

     32: /*****************************************************************/
     33: /*********     GENND ..... GENERAL NESTED DISSECTION     *********/
     34: /*****************************************************************/

     36: /*    PURPOSE - SUBROUTINE GENND FINDS A NESTED DISSECTION*/
     37: /*       ORDERING FOR A GENERAL GRAPH.*/

     39: /*    INPUT PARAMETERS -*/
     40: /*       NEQNS - NUMBER OF EQUATIONS.*/
     41: /*       (XADJ, ADJNCY) - ADJACENCY STRUCTURE PAIR.*/

     43: /*    OUTPUT PARAMETERS -*/
     44: /*       PERM - THE NESTED DISSECTION ORDERING.*/

     46: /*    WORKING PARAMETERS -*/
     47: /*       MASK - IS USED TO MASK OFF VARIABLES THAT HAVE*/
     48: /*              BEEN NUMBERED DURING THE ORDERNG PROCESS.*/
     49: /*       (XLS, LS) - THIS LEVEL STRUCTURE PAIR IS USED AS*/
     50: /*              TEMPORARY STORAGE BY FN../../...*/

     52: /*    PROGRAM SUBROUTINES -*/
     53: /*       FNDSEP, REVRSE.*/
     54: /*****************************************************************/

     56: PetscErrorCode SPARSEPACKgennd(const PetscInt *neqns,const PetscInt *xadj,const PetscInt *adjncy,PetscInt *mask,PetscInt *perm,PetscInt *xls,PetscInt *ls)
     57: {
     58:   /* System generated locals */
     59:   PetscInt i__1;

     61:   /* Local variables */
     62:   PetscInt nsep,root,i;
     63:   PetscInt num;

     66:   /* Parameter adjustments */
     67:   --ls;
     68:   --xls;
     69:   --perm;
     70:   --mask;
     71:   --adjncy;
     72:   --xadj;

     74:   i__1 = *neqns;
     75:   for (i = 1; i <= i__1; ++i) mask[i] = 1;
     76:   num  = 0;
     77:   i__1 = *neqns;
     78:   for (i = 1; i <= i__1; ++i) {
     79: /*           FOR EACH MASKED COMPONENT ...*/
     80: L200:
     81:     if (!mask[i]) goto L300;
     82:     root = i;
     83: /*              FIND A SEPARATOR AND NUMBER THE NODES NEXT.*/
     84:     SPARSEPACKfndsep(&root,&xadj[1],&adjncy[1],&mask[1],&nsep,&perm[num + 1],&xls[1],&ls[1]);
     85:     num += nsep;
     86:     if (num >= *neqns) goto L400;
     87:     goto L200;
     88: L300:
     89:     ;
     90:   }
     91: /*        SINCE SEPARATORS FOUND FIRST SHOULD BE ORDERED*/
     92: /*        LAST, ROUTINE REVRSE IS CALLED TO ADJUST THE*/
     93: /*        ORDERING VECTOR.*/
     94: L400:
     95:   SPARSEPACKrevrse(neqns,&perm[1]);
     96:   return(0);
     97: }