/* ========================================================================== */
/* === CHOLMOD/MATLAB/analyze mexFunction =================================== */
/* ========================================================================== */

/* -----------------------------------------------------------------------------
 * CHOLMOD/MATLAB Module.  Copyright (C) 2005-2006, Timothy A. Davis
 * The CHOLMOD/MATLAB Module is licensed under Version 2.0 of the GNU
 * General Public License.  See gpl.txt for a text of the license.
 * CHOLMOD is also available under other licenses; contact authors for details.
 * http://www.cise.ufl.edu/research/sparse
 * MATLAB(tm) is a Trademark of The MathWorks, Inc.
 * -------------------------------------------------------------------------- */

/* Order a matrix and then analyze it, using CHOLMOD's best-effort ordering.
 * Returns the count of the number of nonzeros in each column of L for the
 * permuted matrix A.
 *
 * Usage:
 *
 *	[p count] = analyze (A)		orders A, using just tril(A)
 *	[p count] = analyze (A,'sym')	orders A, using just tril(A)
 *	[p count] = analyze (A,'row')	orders A*A'
 *	[p count] = analyze (A,'col')	orders A'*A
 *
 * with an optional 3rd parameter:
 *
 *	[p count] = analyze (A,'sym',k)	orders A, using just tril(A)
 *	[p count] = analyze (A,'row',k)	orders A*A'
 *	[p count] = analyze (A,'col',k)	orders A'*A
 *
 *	k=0 is the default.  k != 0 selects the ordering strategy.
 *
 * See analyze.m for more details.
 */

#include "cholmod_matlab.h"

void mexFunction
(
    int nargout,
    mxArray *pargout [ ],
    int nargin,
    const mxArray *pargin [ ]
)
{
    double dummy = 0 ;
    cholmod_factor *L ;
    cholmod_sparse *A, Amatrix, *C, *S ;
    cholmod_common Common, *cm ;
    Int n, transpose, c ;
    char buf [LEN] ;

    /* ---------------------------------------------------------------------- */
    /* start CHOLMOD and set defaults */
    /* ---------------------------------------------------------------------- */

    cm = &Common ;
    cholmod_l_start (cm) ;
    sputil_config (SPUMONI, cm) ;

    /* only do the simplicial analysis (L->Perm and L->ColCount) */
    cm->supernodal = CHOLMOD_SIMPLICIAL ;

    /* ---------------------------------------------------------------------- */
    /* get inputs */
    /* ---------------------------------------------------------------------- */

    if (nargout > 2 || nargin < 1 || nargin > 3)
    {
	mexErrMsgTxt ("Usage: [p count] = analyze (A, mode)") ;
    }
    if (nargin == 3)
    {
	cm->nmethods = mxGetScalar (pargin [2]) ;
	if (cm->nmethods == -1)
	{
	    /* use AMD only */
	    cm->nmethods = 1 ;
	    cm->method [0].ordering = CHOLMOD_AMD ;
	    cm->postorder = TRUE ;
	}
	else if (cm->nmethods == -2)
	{
	    /* use METIS only */
	    cm->nmethods = 1 ;
	    cm->method [0].ordering = CHOLMOD_METIS ;
	    cm->postorder = TRUE ;
	}
	else if (cm->nmethods == -3)
	{
	    /* use NESDIS only */
	    cm->nmethods = 1 ;
	    cm->method [0].ordering = CHOLMOD_NESDIS ;
	    cm->postorder = TRUE ;
	}
    }

    /* ---------------------------------------------------------------------- */
    /* get input matrix A */
    /* ---------------------------------------------------------------------- */

    A = sputil_get_sparse_pattern (pargin [0], &Amatrix, &dummy, cm) ;
    S = (A == &Amatrix) ? NULL : A ;

    /* ---------------------------------------------------------------------- */
    /* get A->stype, default is to use tril(A) */
    /* ---------------------------------------------------------------------- */

    A->stype = -1 ;
    transpose = FALSE ;

    if (nargin > 1)
    {
	buf [0] = '\0' ;
	if (mxIsChar (pargin [1]))
	{
	    mxGetString (pargin [1], buf, LEN) ;
	}
	c = buf [0] ;
	if (tolower (c) == 'r')
	{
	    /* unsymmetric case (A*A') if string starts with 'r' */
	    transpose = FALSE ;
	    A->stype = 0 ;
	}
	else if (tolower (c) == 'c')
	{
	    /* unsymmetric case (A'*A) if string starts with 'c' */
	    transpose = TRUE ;
	    A->stype = 0 ;
	}
	else if (tolower (c) == 's')
	{
	    /* symmetric case (A) if string starts with 's' */
	    transpose = FALSE ;
	    A->stype = -1 ;
	}
	else
	{
	    mexErrMsgTxt ("analyze: unrecognized mode") ;
	}
    }

    if (A->stype && A->nrow != A->ncol)
    {
	mexErrMsgTxt ("analyze: A must be square") ;
    }

    C = NULL ;
    if (transpose)
    {
	/* C = A', and then order C*C' */
	C = cholmod_l_transpose (A, 0, cm) ;
	if (C == NULL)
	{
	    mexErrMsgTxt ("analyze failed") ;
	}
	A = C ;
    }

    n = A->nrow ;

    /* ---------------------------------------------------------------------- */
    /* analyze and order the matrix */
    /* ---------------------------------------------------------------------- */

    L = cholmod_l_analyze (A, cm) ;

    /* ---------------------------------------------------------------------- */
    /* return Perm */
    /* ---------------------------------------------------------------------- */

    pargout [0] = sputil_put_int (L->Perm, n, 1) ;
    if (nargout > 1)
    {
	pargout [1] = sputil_put_int (L->ColCount, n, 0) ;
    }

    /* ---------------------------------------------------------------------- */
    /* free workspace */
    /* ---------------------------------------------------------------------- */

    cholmod_l_free_factor (&L, cm) ;
    cholmod_l_free_sparse (&C, cm) ;
    cholmod_l_free_sparse (&S, cm) ;
    cholmod_l_finish (cm) ;
    cholmod_l_print_common (" ", cm) ;
    /* if (cm->malloc_count != 0) mexErrMsgTxt ("!") ; */
}
