Rounding problem R vs Excel
On Tue, 3 Jun 2003, Mike White wrote:
If the numbers are not represently exactly how does R resolve problems like the one below? Is there something that needs to be set up in the R
What problem exactly?
environment like the number of significant figures?
Printing is controlled by options("digits"): is that what you had in mind?
x<-4.145*100+0.5 x
[1] 415
but
print(x, digits=16)
[1] 414.9999999999999
x - 415 # which would be exact if x were integer
[1] -5.684342e-14
floor(x)
[1] 414
as.integer(x)
[1] 414
trunc(x)
[1] 414
All as expected as 414 < x < 415. Don't confuse the printed representation of an object with the object itself.
Brian D. Ripley, ripley at stats.ox.ac.uk Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595