Re: Infinity as index

[Dirk Laurie <dirk.laurie@...>]

2014-04-24 1:19 GMT+02:00 Rena <hyperhacker@gmail.com>:

> lua_isnan(L, n): returns true if the value at index n is NaN.
> lua_isinfinity(L, n): returns 1 if the value at index n is infinity, -1 if the value is -infinity, and 0 otherwise.

I don't think we need that at the C API level.

In Lua, there are standard idioms:

if x~=x then    -- x is NaN

if 1/x == 0 then    -- x is inf or -inf

if x==1/0 then    -- x is inf

if x==-1/0 then   -- x is -inf

if x==0 then   -- x is 0 or -0

The hardest test of all is to distinguish between 0 and -0.
If you can improve on the following, please post.

if x==0 and 1/x>0 then -- x is 0
if x==0 and 1/x<0 then -- x is -0