#  File src/library/base/R/det.R
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## det now uses Lapack and an LU decomposition.  The method argument is
##     no longer used.
## S-plus' Matrix pkg has arg. "logarithm = TRUE" and returns list
##        (which is necessary for keeping the sign when taking log ..)
## S-plus v 6.x has incorporated the Matrix pkg det as determinant

det <- function(x, ...)
{
    z <- determinant(x, logarithm = TRUE, ...)
    c(z$sign * exp(z$modulus))
}

determinant <- function(x, logarithm = TRUE, ...) UseMethod("determinant")

determinant.matrix <- function(x, logarithm = TRUE, ...)
{
    if ((n <- ncol(x)) != nrow(x))
        stop("'x' must be a square matrix")
    if (n < 1L)
	return(structure(list(modulus =
			      structure(if(logarithm) 0 else 1,
					logarithm = logarithm),
			      sign = 1L),
			 class = "det"))
    if (is.complex(x))
        stop("'determinant' not currently defined for complex matrices")
    ## FIXME: should not be so hard to implement; see
    ##      moddet_ge_real() in ../../../modules/lapack/Lapack.c
    ## the 'sign' would have to be complex z, with |z|=1
    .Internal(det_ge_real(x, logarithm))
}
