# [R] precision problem

Omar Lakkis uofiowa at gmail.com
Wed May 25 16:47:53 CEST 2005

```Thank you all.
all.equal is very helpful since I am also interested in finding the
mismatched prices.

On 5/25/05, John Fox <jfox at mcmaster.ca> wrote:
> Dear Omar,
>
> Perhaps I'm missing something, but why not just subtract one matrix from the
> other and test the difference in relation to the precision that you require
> for the comparison? E.g., to test near equality, something like, abs(A - B)
> < 1e-13.
>
> I hope this helps,
>  John
>
> --------------------------------
> John Fox
> Department of Sociology
> McMaster University
> Hamilton, Ontario
> 905-525-9140x23604
> http://socserv.mcmaster.ca/jfox
> --------------------------------
>
> > -----Original Message-----
> > From: r-help-bounces at stat.math.ethz.ch
> > [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Omar Lakkis
> > Sent: Wednesday, May 25, 2005 9:09 AM
> > To: r-help at stat.math.ethz.ch
> > Subject: [R] precision problem
> >
> > I have prices that I am finding difficult to compare with ==,
> > > and >, due to precision. For example: the numbers should
> > match, with '==', but they differ in the magnitude of 1e-14
> > due to bunch of calculations that I run on them. Programming
> > with java, I am used to implementing a function that compares
> > the difference between the numbers to a pre determined
> > precision factor. This could be very slow when  I have two
> > matrices of numbers that I could otherwise compare with a
> > simple '==', '>'  or '<' in R.
> > What is teh best solution for this problem?
> > Can I control the precision of ==, > and < without having to
> > reimplement the operations in a slow way?
> >
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