Feng
checkout the Brobdingnag package:
> library(Brobdingnag)
> exp(1000)/(exp(1007)+5)
[1] NaN
> as.numeric(exp(as.brob(1000))/(exp(as.brob(1007))+5))
[1] 0.000911882
>
Feng Li wrote:
Dear R,
I have two questions:
1, Why both R and Matlab give 0*Inf==NaN? To my knowledge, it should be zero
mathematically. Am I right?
2, I need to calculate e.g. exp(a)/(exp(b)+c), where both a and b are very
large numbers (>>1000, e.g a=1000, b=1007, and c=5). R gives me NaN when I
use the following command:
exp(1000)/(exp(1007)+5)
[1] NaN
I am pretty sure this should be close to zero. My question is whether there
is a general way to solve this kind of question or should I do some settings
before computing?
Thanks in advance!
Feng
--
Robin K. S. Hankin
Uncertainty Analyst
University of Cambridge
19 Silver Street
Cambridge CB3 9EP
01223-764877
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