[R] How to handle large numbers?
ggrothendieck at gmail.com
Wed Feb 11 15:09:54 CET 2009
Try Ryacas. N means numerically evaluate in
yacas (as we don't want it evaluated on
the R side where we already know we get NaN).
You can explore it somewhat in R via:
curve(exp(x)/(exp(x+7)+5), 1, 500)
On Wed, Feb 11, 2009 at 5:40 AM, Feng Li <840116 at gmail.com> 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:
>  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 Li
> Department of Statistics
> Stockholm University
> 106 91 Stockholm, Sweden
> [[alternative HTML version deleted]]
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