Re: factorial of negative numbers

Peter Eisentraut <peter(dot)eisentraut(at)2ndquadrant(dot)com> writes:
> Adjacent to the discussion in [0] I wanted to document the factorial()
> function and expand the tests for that slightly with some edge cases.
> ...
> I propose to change this to error out for negative numbers.

+1 for all of this, with a couple trivial nitpicks about the error
changes:

* I'd have written the error as "factorial of a negative number is
undefined" ... not sure what a grammar stickler would say about it,
but that seems more natural to me.

* I'd leave the "if (num <= 1)" test after the error check as-is;
it's probably a shade cheaper than "if (num == 0 || num == 1)".

regards, tom lane