[R] precision problem
John Fox
jfox at mcmaster.ca
Thu May 26 03:09:52 CEST 2005
Dear Omar,
It wasn't clear to me from your original question that you wanted to test
that *all* the corresponding entries were equal, as opposed to each
individual entry.
In any event, I don't think that you'll find a similar function for testing
inequality, so you can do as you suggest, but of course without abs().
Regards,
John
--------------------------------
John Fox
Department of Sociology
McMaster University
Hamilton, Ontario
Canada L8S 4M4
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 10:08 AM
> To: r-help at stat.math.ethz.ch
> Subject: Re: [R] precision problem
>
> all.equal is helpful when I am comparing equality of two matrices.
> However, when I am comparing two individual number with > or
> < is my best bet doing if( abs(x - y) < tolerence) or is
> there a function like all.equal that has the same default tolerence?
>
> On 5/25/05, Omar Lakkis <uofiowa at gmail.com> wrote:
> > 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
> > > Canada L8S 4M4
> > > 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?
> > > >
> > > > ______________________________________________
> > > > R-help at stat.math.ethz.ch mailing list
> > > > https://stat.ethz.ch/mailman/listinfo/r-help
> > > > PLEASE do read the posting guide!
> > > > http://www.R-project.org/posting-guide.html
> > >
> > >
> >
>
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