# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Library General Public
# License as published by the Free Software Foundation; either
# version 2 of the License, or (at your option) any later version.
#
# This library 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 Library General Public License for more details.
#
# You should have received a copy of the GNU Library General
# Public License along with this library; if not, write to the
# Free Foundation, Inc., 59 Temple Place, Suite 330, Boston,
# MA  02111-1307  USA

# Copyrights (C)
# for this R-port:
#   1999 - 2008, Diethelm Wuertz, Rmetrics Foundation, GPL
#   Diethelm Wuertz <wuertz@itp.phys.ethz.ch>
#   www.rmetrics.org
# for the code accessed (or partly included) from other R-ports:
#   see R's copyright and license files
# for the code accessed (or partly included) from contributed R-ports
# and other sources
#   see Rmetrics's copyright file


################################################################################
# LINEAR ALGEBRA:           DESCRIPTION:
#  rk                        Returns the rank of a matrix
################################################################################


rk <-
    function(x, method = c("qr", "chol"))
{
    # A function implemented by Diethelm Wuertz

    # Description:
    #   Returns the rank of a matrix

    # FUNCTION:

    # Rank:
    method = method[1]
    if (method == "chol") {
        ans = attr(chol(x, pivot = TRUE), "rank")
    } else {
        ans = qr(x)$rank
    }

    # Return Value:
    ans
}


################################################################################