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// CXSparse/MATLAB/CSparse/cs_scc_mex: strongly connected components
// CXSparse, Copyright (c) 2006-2022, Timothy A. Davis. All Rights Reserved.
// SPDX-License-Identifier: LGPL-2.1+
#include "cs_mex.h"
/* [p,r] = cs_scc (A) finds the strongly connected components of A */
void mexFunction
(
int nargout,
mxArray *pargout [ ],
int nargin,
const mxArray *pargin [ ]
)
{
cs_dl Amatrix, *A ;
cs_dld *D ;
int64_t n, j, *Ap2 ;
if (nargout > 2 || nargin != 1)
{
mexErrMsgTxt ("Usage: [p,r] = cs_scc(A)") ;
}
A = cs_dl_mex_get_sparse (&Amatrix, 1, 0, pargin [0]) ; /* get A */
/* cs_scc modifies A->p and then restores it (in cs_dfs). Avoid the issue
* of a mexFunction modifying its input (even temporarily) by making a copy
* of A->p. This issue does not arise in cs_dmperm, because that function
* applies cs_scc to a submatrix C, not to A directly. */
n = A->n ;
Ap2 = cs_dl_malloc (n+1, sizeof (int64_t)) ;
for (j = 0 ; j <= n ; j++) Ap2 [j] = A->p [j] ;
A->p = Ap2 ;
D = cs_dl_scc (A) ; /* find conn. comp. */
pargout [0] = cs_dl_mex_put_int (D->p, n, 1, 0) ; /* return p */
pargout [1] = cs_dl_mex_put_int (D->r, D->nb+1, 1, 0) ; /* return r */
cs_dl_dfree (D) ;
cs_dl_free (Ap2) ; /* free the copy of A->p */
}
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