Re: integer exponentiation with negative exponent

[Coda Highland <chighland@...>]

On Fri, Apr 11, 2014 at 7:23 PM, Peng Zhicheng
<pengzhicheng1986@gmail.com> wrote:
> having looked at the `luaV_pow' in lvm.c, I found it is _intentionally_
> reported as an error (at least
> for current work version) -- since this function translates `pow' into a
> serial of `mult' operations.
> But this `luaV_pow' is only called when both operands of the OP_POW are
> integers. for float point numbers,
> `l_mathop(pow)' is used instead.
> Lua 5.2 don't have two different internal number representations, thus the
> negative exponent is OK.
>
>
> but, same as Rena, I don't like this behavior either;
> one reason is the potential to break existing code, as Rena pointed.
> another reason is that I think users should see as little differece between
> the number representations as possible,
> ans the pow is not concerned as much as the div operator whether it is an
> integer or float point operaton.
>
> is the gain (if any) of a special integer pow operation worth the semantic
> change?

It's probably faster, but the problem can be addressed by also using
the floating-point version when the RHS operand is negative. It seems
a simple enough change to me.

/s/ Adam