/* cs_permute: permute a sparse matrix */
void mexFunction
(
int nargout,
mxArray *pargout [ ],
int nargin,
const mxArray *pargin [ ]
)
{
cs Amatrix, *A, *C, *D ;
int ignore, *P, *Q, *Pinv ;
if (nargout > 1 || nargin != 3)
{
mexErrMsgTxt ("Usage: C = cs_permute(A,p,q)") ;
}
A = cs_mex_get_sparse (&Amatrix, 0, 1, pargin [0]) ; /* get A */
P = cs_mex_get_int (A->m, pargin [1], &ignore, 1) ; /* get P */
Q = cs_mex_get_int (A->n, pargin [2], &ignore, 1) ; /* get Q */
Pinv = cs_pinv (P, A->m) ; /* P = Pinv' */
C = cs_permute (A, Pinv, Q, 1) ; /* C = A(p,q) */
D = cs_transpose (C, 1) ; /* sort C via double transpose */
cs_spfree (C) ;
C = cs_transpose (D, 1) ;
cs_spfree (D) ;
pargout [0] = cs_mex_put_sparse (&C) ; /* return C */
cs_free (Pinv) ;
cs_free (P) ;
cs_free (Q) ;
}
/* cs_symperm: symmetric permutation of a symmetric sparse matrix. */
void mexFunction
(
int nargout,
mxArray *pargout [ ],
int nargin,
const mxArray *pargin [ ]
)
{
cs Amatrix, *A, *C, *D ;
csi ignore, n, *P, *Pinv ;
if (nargout > 1 || nargin != 2)
{
mexErrMsgTxt ("Usage: C = cs_symperm(A,p)") ;
}
A = cs_mex_get_sparse (&Amatrix, 1, 1, pargin [0]) ;
n = A->n ;
P = cs_mex_get_int (n, pargin [1], &ignore, 1) ; /* get P */
Pinv = cs_pinv (P, n) ; /* P=Pinv' */
C = cs_symperm (A, Pinv, 1) ; /* C = A(p,p) */
D = cs_transpose (C, 1) ; /* sort C */
cs_spfree (C) ;
C = cs_transpose (D, 1) ;
cs_spfree (D) ;
pargout [0] = cs_mex_put_sparse (&C) ; /* return C */
cs_free (P) ;
cs_free (Pinv) ;
}
/* cs_updown: sparse Cholesky update/downdate (rank-1 or multiple rank) */
void mexFunction
(
int nargout,
mxArray *pargout [ ],
int nargin,
const mxArray *pargin [ ]
)
{
cs Lmatrix, *Lin, Cmatrix, *C, *L, Cvector, *Cvec ;
int ignore, j, k, n, lnz, *parent, sigma = 1, cp [2] ;
char sigma_string [20] ;
if (nargout > 1 || nargin < 3 || nargin > 4)
{
mexErrMsgTxt ("Usage: L = cs_updown(L,C,parent,sigma)") ;
}
Lin = cs_mex_get_sparse (&Lmatrix, 1, 1, pargin [0]) ; /* get input L */
n = Lin->n ;
if (nargin > 3 && mxIsChar (pargin [3]))
{
mxGetString (pargin [3], sigma_string, 8) ;
sigma = (sigma_string [0] == '-') ? (-1) : 1 ;
}
/* make a copy of L (this can take more work than updating L itself) */
lnz = Lin->p [n] ;
L = cs_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_mex_get_sparse (&Cmatrix, 0, 1, pargin [1]) ;
parent = cs_mex_get_int (n, pargin [2], &ignore, 0) ; /* get parent */
/* 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] ;
cs_updown (L, sigma, Cvec, parent) ; /* update/downdate */
}
pargout [0] = cs_mex_put_sparse (&L) ; /* return new L */
}
