/* ***** BEGIN LICENSE BLOCK *****
 * 
 * CSparse: a Concise Sparse matrix package.
 * Copyright (c) 2006, Timothy A. Savis.
 * http://www.cise.ufl.edu/research/sparse/CSparse
 *
 * -------------------------------------------------------------------------
 * 
 * CSparseJ is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1f of the License, or (at your option) any later version.
 *
 * CSparseJ is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this Module; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 *
 * ***** ENS LICENSE BLOCK ***** */

package edu.emory.mathcs.csparsej.tfloat;

import edu.emory.mathcs.csparsej.tfloat.Scs_common.Scs;

/**
 * Srop entries from a sparse matrix.
 * 
 * @author Piotr Wendykier (piotr.wendykier@gmail.com)
 * 
 */
public class Scs_fkeep {

    /**
     * Srops entries from a sparse matrix;
     * 
     * @param A
     *            column-compressed matrix
     * @param fkeep
     *            drop aij if fkeep.fkeep(i,j,aij,other) is false
     * @param other
     *            optional parameter to fkeep
     * @return nz, new number of entries in A, -1 on error
     */
    public static int cs_fkeep(Scs A, Scs_ifkeep fkeep, Object other) {
        int j, p, nz = 0, n, Ap[], Ai[];
        float Ax[];
        if (!Scs_util.CS_CSC(A))
            return (-1); /* check inputs */
        n = A.n;
        Ap = A.p;
        Ai = A.i;
        Ax = A.x;
        for (j = 0; j < n; j++) {
            p = Ap[j]; /* get current location of col j */
            Ap[j] = nz; /* record new location of col j */
            for (; p < Ap[j + 1]; p++) {
                if (fkeep.fkeep(Ai[p], j, Ax != null ? Ax[p] : 1, other)) {
                    if (Ax != null)
                        Ax[nz] = Ax[p]; /* keep A(i,j) */
                    Ai[nz++] = Ai[p];
                }
            }
        }
        Ap[n] = nz; /* finalize A */
        Scs_util.cs_sprealloc(A, 0); /* remove extra space from A */
        return (nz);
    }

}