1 #include "cs.h"
2 /* xi [top...n-1] = nodes reachable from graph of G*P' via nodes in B(:,k).
3 * xi [n...2n-1] used as workspace */
cs_reach(cs * G,const cs * B,CS_INT k,CS_INT * xi,const CS_INT * pinv)4 CS_INT cs_reach (cs *G, const cs *B, CS_INT k, CS_INT *xi, const CS_INT *pinv)
5 {
6 CS_INT p, n, top, *Bp, *Bi, *Gp ;
7 if (!CS_CSC (G) || !CS_CSC (B) || !xi) return (-1) ; /* check inputs */
8 n = G->n ; Bp = B->p ; Bi = B->i ; Gp = G->p ;
9 top = n ;
10 for (p = Bp [k] ; p < Bp [k+1] ; p++)
11 {
12 if (!CS_MARKED (Gp, Bi [p])) /* start a dfs at unmarked node i */
13 {
14 top = cs_dfs (Bi [p], G, top, xi, xi+n, pinv) ;
15 }
16 }
17 for (p = top ; p < n ; p++) CS_MARK (Gp, xi [p]) ; /* restore G */
18 return (top) ;
19 }
20