[R] Computational differences in R vs Excel

[David Winsemius]

On Nov 19, 2013, at 6:02 AM, S Ellison wrote:

>>> For example, i am performing this simple arithmetic:
>>>    23-(1.346493052*16)+(.663965156*11)+(.008569426*5)-15.23480728
>>> 
>>> R gives the result --> -6.432232271
> 
> 
> My machine (win32, R 3.0.1) gives -6.432232266
> 
> Something about your machine, or typing, is different.

I get the same, at least when printing to the same degree of accuracy:

> x <- 23-(1.346493052*16)+(.663965156*11)+(.008569426*5)-15.23480728 
> print(x, digits=10)
[1] -6.432232266


Mac OSX 10.7.5, R 3.0.2

> It shouldn't be R, as the help system implies it uses the same precision and IEEE floating point rules for all platforms....
> 
> 
> S Ellison


-- 
David Winsemius
Alameda, CA, USA