# File src/library/base/R/eigen.R
# Part of the R package, https://www.R-project.org
#
# Copyright (C) 1995-2015 The R Core Team
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program 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 General Public License for more details.
#
# A copy of the GNU General Public License is available at
# https://www.R-project.org/Licenses/
isSymmetric <- function(object, ...) UseMethod("isSymmetric")
isSymmetric.matrix <- function(object, tol = 100*.Machine$double.eps, ...)
{
if(!is.matrix(object)) return(FALSE) ## we test for symmetric *matrix*
## cheap pretest: is it square?
d <- dim(object)
if(d[1L] != d[2L]) return(FALSE)
test <-
if(is.complex(object))
all.equal.numeric(object, Conj(t(object)), tolerance = tol, ...)
else # numeric, character, ..
all.equal(object, t(object), tolerance = tol, ...)
isTRUE(test)
}
eigen <- function(x, symmetric, only.values = FALSE, EISPACK = FALSE)
{
x <- unname(as.matrix(x))
n <- nrow(x)
if (!n) stop("0 x 0 matrix")
if (n != ncol(x)) stop("non-square matrix in 'eigen'")
n <- as.integer(n)
if(is.na(n)) stop("invalid nrow(x)")
complex.x <- is.complex(x)
if (!all(is.finite(x))) stop("infinite or missing values in 'x'")
if(missing(symmetric)) symmetric <- isSymmetric.matrix(x)
if (symmetric) {
z <- if(!complex.x) .Internal(La_rs(x, only.values))
else .Internal(La_rs_cmplx(x, only.values))
ord <- rev(seq_along(z$values))
} else {
z <- if(!complex.x) .Internal(La_rg(x, only.values))
else .Internal(La_rg_cmplx(x, only.values))
ord <- sort.list(Mod(z$values), decreasing = TRUE)
}
return(list(values = z$values[ord],
vectors = if (!only.values) z$vectors[, ord, drop = FALSE]))
}
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