Actual source code: rootls.c

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

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

  6: /*****************************************************************/
  7: /*********     ROOTLS ..... ROOTED LEVEL STRUCTURE      **********/
  8: /*****************************************************************/
  9: /*    PURPOSE - ROOTLS GENERATES THE LEVEL STRUCTURE ROOTED */
 10: /*       AT THE INPUT NODE CALLED ROOT. ONLY THOSE NODES FOR*/
 11: /*       WHICH MASK IS NONZERO WILL BE CONSIDERED.*/
 12: /*                                                */
 13: /*    INPUT PARAMETERS -                          */
 14: /*       ROOT - THE NODE AT WHICH THE LEVEL STRUCTURE IS TO*/
 15: /*              BE ROOTED.*/
 16: /*       (XADJ, ADJNCY) - ADJACENCY STRUCTURE PAIR FOR THE*/
 17: /*              GIVEN GRAPH.*/
 18: /*       MASK - IS USED TO SPECIFY A SECTION SUBGRAPH. NODES*/
 19: /*              WITH MASK(I)=0 ARE IGNORED.*/
 20: /*    OUTPUT PARAMETERS -*/
 21: /*       NLVL - IS THE NUMBER OF LEVELS IN THE LEVEL STRUCTURE.*/
 22: /*       (XLS, LS) - ARRAY PAIR FOR THE ROOTED LEVEL STRUCTURE.*/
 23: /*****************************************************************/
 24: PetscErrorCode SPARSEPACKrootls(const PetscInt *root, const PetscInt *xadj, const PetscInt *adjncy, PetscInt *mask, PetscInt *nlvl, PetscInt *xls, PetscInt *ls)
 25: {
 26:   /* System generated locals */
 27:   PetscInt i__1, i__2;

 29:   /* Local variables */
 30:   PetscInt node, i, j, jstop, jstrt, lbegin, ccsize, lvlend, lvsize, nbr;

 32:   /*       INITIALIZATION ...*/

 34:   PetscFunctionBegin;
 35:   /* Parameter adjustments */
 36:   --ls;
 37:   --xls;
 38:   --mask;
 39:   --adjncy;
 40:   --xadj;

 42:   mask[*root] = 0;
 43:   ls[1]       = *root;
 44:   *nlvl       = 0;
 45:   lvlend      = 0;
 46:   ccsize      = 1;
 47: /*       LBEGIN IS THE POINTER TO THE BEGINNING OF THE CURRENT*/
 48: /*       LEVEL, AND LVLEND POINTS TO THE END OF THIS LEVEL.*/
 49: L200:
 50:   lbegin = lvlend + 1;
 51:   lvlend = ccsize;
 52:   ++(*nlvl);
 53:   xls[*nlvl] = lbegin;
 54:   /*       GENERATE THE NEXT LEVEL BY FINDING ALL THE MASKED */
 55:   /*       NEIGHBORS OF NODES IN THE CURRENT LEVEL.*/
 56:   i__1 = lvlend;
 57:   for (i = lbegin; i <= i__1; ++i) {
 58:     node  = ls[i];
 59:     jstrt = xadj[node];
 60:     jstop = xadj[node + 1] - 1;
 61:     if (jstop < jstrt) goto L400;
 62:     i__2 = jstop;
 63:     for (j = jstrt; j <= i__2; ++j) {
 64:       nbr = adjncy[j];
 65:       if (!mask[nbr]) goto L300;
 66:       ++ccsize;
 67:       ls[ccsize] = nbr;
 68:       mask[nbr]  = 0;
 69:     L300:;
 70:     }
 71:   L400:;
 72:   }
 73:   /*       COMPUTE THE CURRENT LEVEL WIDTH.*/
 74:   /*       IF IT IS NONZERO, GENERATE THE NEXT LEVEL.*/
 75:   lvsize = ccsize - lvlend;
 76:   if (lvsize > 0) goto L200;
 77:   /*       RESET MASK TO ONE FOR THE NODES IN THE LEVEL STRUCTURE.*/
 78:   xls[*nlvl + 1] = lvlend + 1;
 79:   i__1           = ccsize;
 80:   for (i = 1; i <= i__1; ++i) {
 81:     node       = ls[i];
 82:     mask[node] = 1;
 83:   }
 84:   PetscFunctionReturn(PETSC_SUCCESS);
 85: }