Re: Missing pow function?

[Edgar Toernig <froese@...>]

Hi,

Marius Kjeldahl wrote:
> 
> I'm trying to use the pow function, but it does not work.

I assume you are trying something like pow(a,b)?  Try a^b instead.
Power is an operator, not a function.

> While most of the mathematical functions are defined in the luaL_reg
> mathlib structure in lmathlib.c, it seems pow is defined differently in
> lua_mathlibopen:
> 
>    lua_pushcfunction(L, math_pow);
>    lua_settagmethod(L, LUA_TNUMBER, "pow");
> 
> I'm new to lua, but I would guess this code is supposed to demo how to
> define pow as a function in a different manner than using the luaL_reg
> mathlib structure.

It's not a demo ;-)  It registers a handler that is called when the ^ (pow)
operator is applied to a number.

(The pow-function requires C's math library and is therefore not in the
standard Lua executor but together with all other math functions in Lua's
math library.)

> Is pow supposed to be supported, and if so can I safely assume that it
> is a bug for now (and add it the same way the other functions are being
> used)?

Not a bug, just a misunderstanding.  You could of course put it also in
the luaL_reg mathlib structure and get it as a function.  But the ^ oper-
ator may be more comfortable.

Ciao, ET.