Jean-Claude Arbaut wrote:

> Hi,
> 
> is there a limit on a Bignum size ?

AFAIK no, apart from increasingly long computation times.

> I get this:
> 
> irb> a=2**262144; a % 10**20
> => 62605349934298300416
> 
> irb> a=2**262145; a
> (irb):1: warning: in a**b, b may be too big
> => Infinity

What version of Ruby do you have? I ran the same test and didn't get this
message. And what platform? Mine:

$ ruby -v
ruby 1.8.4 (2005-12-24) [i386-linux]

Using irb I computed 2**262145 and compared it to an authoritative source,
it is correct, no errors or warnings.

// snip examples

> Is there a bug in the ** method ?

On my system, using your examples, I cannot produce any of the warnings you
are showing, and the results look correct.

-- 
Paul Lutus
http://www.arachnoid.com