[R] Best way to remove double precision round off chaff

Bert Gunter gunter.berton at gene.com
Mon Jun 14 01:32:15 CEST 2010


Many print methods have specific options to control this: ?print.default

See also the "digits" and "scipen" settings in ?options for global control
(these can be put in your startup file, for example).

See also ?format and e.g. ?sprintf for more precise control of print format.

All of this has to do with what is displayed and does not change the
underlying values, of course, which round() and friends do.


Bert Gunter
Genentech Nonclinical Statistics

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On
Behalf Of Jason Rupert
Sent: Sunday, June 13, 2010 4:24 PM
To: R Project Help
Subject: [R] Best way to remove double precision round off chaff

I would like to get rid of the double precision round off chaff, so is the
following the best way to handle it? 

> 0.625-0.8+0.45-0.275
[1] -5.551115e-17
> round(0.625-0.8+0.45-0.275, digits=4)
[1] 0

Motivation for removing the chaff is for no other reason than to titty up
the digits for display purposes and to help quicken the analysis of values
that most definitely should be zero. 

Thanks for any insights and feedback.

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