Hi,

2007/6/9, Dann Corbit <[EMAIL PROTECTED]>:
It makes sense with factorial function to do an error check on the
domain.  Calculate beforehand, and figure out what the largest sensible
domain value is.


well, in fact what we need is to calculate log10(n!) first to see if
the result will get exceeded.


For instance, in Maple, I get this:
> y:=92838278!;
Error, object too large
>

The error message returns instantly.

For reasonably large values, it might make sense to pre-compute
factorials and store them in an array.
It should also be possible to
store 1/2 of Pascal's triangle in memory and demand load that memory
segment the first time someone asks for factorials or combinations or
permutations.

there may be too much memories to waste in that case... :-(

Regards
CUI Shijun

---------------------------(end of broadcast)---------------------------
TIP 4: Have you searched our list archives?

              http://archives.postgresql.org

Reply via email to