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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Do not modify this file since it was automatically generated from:
%
% isZero.R
%
% by the Rdoc compiler part of the R.oo package.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\name{isZero}
\alias{isZero.default}
\alias{isZero}
\title{Checks if a value is (close to) zero or not}
\usage{
\method{isZero}{default}(x, neps=1, eps=.Machine$double.eps, ...)
}
\description{
Checks if a value (or a vector of values) is (close to) zero or not
where "close" means if the absolute value is less than \code{neps*eps}.
\emph{Note that \code{x == 0} will not work in all cases.}
By default \code{eps} is the smallest possible floating point value
that can be represented by the running machine, i.e.
\code{.Machine$double.eps} and \code{neps} is one.
By changing \code{neps} it is easy to adjust how close to zero "close"
means without having to know the machine precision (or remembering how
to get it).
}
\arguments{
\item{x}{A \code{\link[base]{vector}} of values.}
\item{eps}{The smallest possible floating point.}
\item{neps}{A scale factor of \code{eps} specifying how close to zero
"close" means. If \code{eps} is the smallest value such that
\code{1 + eps != 1}, i.e. \code{.Machine$double.eps}, \code{neps} must
be greater or equal to one.}
\item{...}{Not used.}
}
\value{Returns a \code{\link[base]{logical}} \code{\link[base]{vector}} indicating if the elements are zero or not.}
\author{Henrik Bengtsson}
\seealso{
\code{\link[base]{all.equal}}().
\code{\link[base]{Comparison}}.
\code{\link[base:zMachine]{.Machine}}.
}
\examples{
x <- 0
print(x == 0) # TRUE
print(isZero(x)) # TRUE
x <- 1
print(x == 0) # FALSE
print(isZero(x)) # FALSE
x <- .Machine$double.eps
print(x == 0) # FALSE
print(isZero(x)) # FALSE
x <- 0.9*.Machine$double.eps
print(x == 0) # FALSE
print(isZero(x)) # TRUE
# From help(Comparisions)
x1 <- 0.5 - 0.3
x2 <- 0.3 - 0.1
print(x1 - x2)
print(x1 == x2) # FALSE on most machines
print(identical(all.equal(x1, x2), TRUE)) # TRUE everywhere
print(isZero(x1-x2)) # TRUE everywhere
}
\keyword{logic}
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