cs_reach.c

/*
 * CXSPARSE: a Concise Sparse Matrix package - Extended.
 * Copyright (c) 2006-2009, Timothy A. Davis.
 * http://www.cise.ufl.edu/research/sparse/CXSparse
 * 
 * CXSparse is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * 
 * CXSparse is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this Module; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include "cs.h"
/* xi [top...n-1] = nodes reachable from graph of G*P' via nodes in B(:,k).
 * xi [n...2n-1] used as workspace */
CS_INT cs_reach (cs *G, const cs *B, CS_INT k, CS_INT *xi, const CS_INT *pinv)
{
    CS_INT p, n, top, *Bp, *Bi, *Gp ;
    if (!CS_CSC (G) || !CS_CSC (B) || !xi) return (-1) ;    /* check inputs */
    n = G->n ; Bp = B->p ; Bi = B->i ; Gp = G->p ;
    top = n ;
    for (p = Bp [k] ; p < Bp [k+1] ; p++)
    {
        if (!CS_MARKED (Gp, Bi [p]))    /* start a dfs at unmarked node i */
        {
            top = cs_dfs (Bi [p], G, top, xi, xi+n, pinv) ;
        }
    }
    for (p = top ; p < n ; p++) CS_MARK (Gp, xi [p]) ;  /* restore G */
    return (top) ;
}