[R] question about precision, floor, and powers of two.

[Berton Gunter]

> In this particular case, it is slightly odd that we can't get an exact
> answer for operations that could in principle be carried out using
> integer arithmetic, but we're actually calculating log(8)/log(2).
> 
> (Curiously, the same effect is not seen on Linux or Solaris until 
> 
>  > log2(2^29)-29
> [1] 3.552714e-15
> 
>

But it's a nice example of the risks of using tests for exact equality (via
==, say)with floating point arithmetic -- even when it **seems** that we
have integers. I'll bet a bunch of my code would flop because of this.

-- Bert Gunter
Genentech Non-Clinical Statistics
South San Francisco, CA
 
"The business of the statistician is to catalyze the scientific learning
process."  - George E. P. Box