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//------------------------------------------------------------------------------
// dimacs10/dimacs10_convert_to_graph.c
//------------------------------------------------------------------------------
// DIMACS10, Copyright (c) 2011, Timothy A Davis. All Rights Reserved.
// SPDX-License-Identifier: BSD-3-clause
//------------------------------------------------------------------------------
#include "mex.h"
/* convert_to_graph mexFunction
function S = convert_to_graph (A, binary)
if (nargin < 2)
binary = 0 ;
end
S = tril (A,-1) + triu (A,1) ;
if (binary)
S = spones (S) ;
end
Ignores the imaginary part of a complex matrix A.
*/
void mexFunction
(
int nargout,
mxArray *pargout [ ],
int nargin,
const mxArray *pargin [ ]
)
{
mwSignedIndex *Ap, *Ai, *Sp, *Si, m, n, nz, j, p, i ;
double *Sx, *Ax ;
int binary ;
if (nargin < 1 || nargin > 2 || nargout > 1)
{
mexErrMsgTxt ("usage: S = convert_to_graph (A, binary)") ;
}
/* get the input A matrix */
Ap = (mwSignedIndex *) mxGetJc (pargin [0]) ;
Ai = (mwSignedIndex *) mxGetIr (pargin [0]) ;
Ax = mxGetPr (pargin [0]) ;
m = mxGetM (pargin [0]) ;
n = mxGetN (pargin [0]) ;
nz = Ap [n] ;
if (nz == 0) nz = 1 ;
/* get the 2nd input argument */
binary = (nargin < 2) ? 0 : ((int) mxGetScalar (pargin [1])) ;
/* allocate the output matrix */
pargout [0] = mxCreateSparse (m, n, nz, mxREAL) ;
Sp = (mwSignedIndex *) mxGetJc (pargout [0]) ;
Si = (mwSignedIndex *) mxGetIr (pargout [0]) ;
Sx = mxGetPr (pargout [0]) ;
/* strip the diagonal from A */
nz = 0 ;
for (j = 0 ; j < n ; j++)
{
Sp [j] = nz ;
for (p = Ap [j] ; p < Ap [j+1] ; p++)
{
i = Ai [p] ;
if (i != j)
{
Si [nz] = i ;
if (!binary) Sx [nz] = Ax [p] ;
nz++ ;
}
}
}
Sp [n] = nz ;
/* convert the result to binary, if requested */
if (binary)
{
for (p = 0 ; p < nz ; p++)
{
Sx [p] = 1 ;
}
}
}
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