cs_ereach.c
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00001 #include "cs.h"
00002 /* find nonzero pattern of Cholesky L(k,1:k-1) using etree and triu(A(:,k)) */
00003 int cs_ereach (const cs *A, int k, const int *parent, int *s, int *w)
00004 {
00005     int i, p, n, len, top, *Ap, *Ai ;
00006     if (!CS_CSC (A) || !parent || !s || !w) return (-1) ;   /* check inputs */
00007     top = n = A->n ; Ap = A->p ; Ai = A->i ;
00008     CS_MARK (w, k) ;                /* mark node k as visited */
00009     for (p = Ap [k] ; p < Ap [k+1] ; p++)
00010     {
00011         i = Ai [p] ;                /* A(i,k) is nonzero */
00012         if (i > k) continue ;       /* only use upper triangular part of A */
00013         for (len = 0 ; !CS_MARKED (w,i) ; i = parent [i]) /* traverse up etree*/
00014         {
00015             s [len++] = i ;         /* L(k,i) is nonzero */
00016             CS_MARK (w, i) ;        /* mark i as visited */
00017         }
00018         while (len > 0) s [--top] = s [--len] ; /* push path onto stack */
00019     }
00020     for (p = top ; p < n ; p++) CS_MARK (w, s [p]) ;    /* unmark all nodes */
00021     CS_MARK (w, k) ;                /* unmark node k */
00022     return (top) ;                  /* s [top..n-1] contains pattern of L(k,:)*/
00023 }


hogman_minimal
Author(s): Maintained by Juergen Sturm
autogenerated on Mon Oct 6 2014 00:06:58