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// CXSparse/MATLAB/CSparse/cs_updown_mex: sparse Cholesky update/downdate
// CXSparse, Copyright (c) 2006-2022, Timothy A. Davis. All Rights Reserved.
// SPDX-License-Identifier: LGPL-2.1+
#include "cs_mex.h"
/* cs_updown: sparse Cholesky update/downdate (rank-1 or multiple rank) */
void mexFunction
(
int nargout,
mxArray *pargout [ ],
int nargin,
const mxArray *pargin [ ]
)
{
int64_t ignore, j, k, n, lnz, *parent, sigma = 1, cp [2], ok ;
char sigma_string [20] ;
if (nargout > 1 || nargin < 3 || nargin > 4)
{
mexErrMsgTxt ("Usage: L = cs_updown(L,C,parent,sigma)") ;
}
if (nargin > 3 && mxIsChar (pargin [3]))
{
mxGetString (pargin [3], sigma_string, 8) ;
sigma = (sigma_string [0] == '-') ? (-1) : 1 ;
}
n = mxGetN (pargin [0]) ;
parent = cs_dl_mex_get_int (n, pargin [2], &ignore, 0) ; /* get parent*/
if (mxIsComplex (pargin [0]) || mxIsComplex (pargin [1]))
{
#ifndef NCOMPLEX
cs_cl Lmatrix, *Lin, Cmatrix, *C, *L, Cvector, *Cvec ;
/* get input L, and copy MATLAB complex to C complex type */
Lin = cs_cl_mex_get_sparse (&Lmatrix, 1, pargin [0]) ;
/* make a copy of L (this can take more work than updating L itself) */
lnz = Lin->p [n] ;
L = cs_cl_spalloc (n, n, lnz, 0, 0) ;
for (j = 0 ; j <= n ; j++) L->p [j] = Lin->p [j] ;
for (k = 0 ; k < lnz ; k++) L->i [k] = Lin->i [k] ;
/* complex values already copied into Lin->x, use shallow copy for L */
L->x = Lin->x ;
cs_mex_check (0, n, -1, 0, 1, 1, pargin [1]) ; /* get C */
C = cs_cl_mex_get_sparse (&Cmatrix, 0, pargin [1]) ;
/* do the update one column at a time */
Cvec = &Cvector ;
Cvec->m = n ;
Cvec->n = 1 ;
Cvec->p = cp ;
Cvec->nz = -1 ;
cp [0] = 0 ;
for (k = 0 ; k < C->n ; k++)
{
/* extract C(:,k) */
cp [1] = C->p [k+1] - C->p [k] ;
Cvec->nzmax = cp [1] ;
Cvec->i = C->i + C->p [k] ;
Cvec->x = C->x + C->p [k] ;
/* update/downdate */
ok = cs_cl_updown (L, sigma, Cvec, parent) ;
if (!ok) mexErrMsgTxt ("matrix is not positive definite") ;
}
/* return new L */
pargout [0] = cs_cl_mex_put_sparse (&L) ;
cs_cl_free (C->x) ; /* free complex copy of C */
#else
mexErrMsgTxt ("complex matrices not supported") ;
#endif
}
else
{
cs_dl Lmatrix, *Lin, Cmatrix, *C, *L, Cvector, *Cvec ;
/* get input L */
Lin = cs_dl_mex_get_sparse (&Lmatrix, 1, 1, pargin [0]) ;
/* make a copy of L (this can take more work than updating L itself) */
lnz = Lin->p [n] ;
L = cs_dl_spalloc (n, n, lnz, 1, 0) ;
for (j = 0 ; j <= n ; j++) L->p [j] = Lin->p [j] ;
for (k = 0 ; k < lnz ; k++) L->i [k] = Lin->i [k] ;
for (k = 0 ; k < lnz ; k++) L->x [k] = Lin->x [k] ;
cs_mex_check (0, n, -1, 0, 1, 1, pargin [1]) ; /* get C */
C = cs_dl_mex_get_sparse (&Cmatrix, 0, 1, pargin [1]) ;
/* do the update one column at a time */
Cvec = &Cvector ;
Cvec->m = n ;
Cvec->n = 1 ;
Cvec->p = cp ;
Cvec->nz = -1 ;
cp [0] = 0 ;
for (k = 0 ; k < C->n ; k++)
{
/* extract C(:,k) */
cp [1] = C->p [k+1] - C->p [k] ;
Cvec->nzmax = cp [1] ;
Cvec->i = C->i + C->p [k] ;
Cvec->x = C->x + C->p [k] ;
/* update/downdate */
ok = cs_dl_updown (L, sigma, Cvec, parent) ;
if (!ok) mexErrMsgTxt ("matrix is not positive definite") ;
}
/* return new L */
pargout [0] = cs_dl_mex_put_sparse (&L) ;
}
}
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