Re: Bug with math.log

[KHMan <keinhong@...>]

On 3/5/2014 3:29 AM, Dio Darkclainer wrote:
> I found new strangeness:
>
> math.floor(math.log(2^n, 2)^a)) --> n^a - 1

Yeah, this is not a surprising thing to some of us.

Tell us what your OS and compiler combination is.

Some older math libraries for certain compiler and OS combinations 
are known to produce such results. Try a short C program and 
you'll get the same result. Good math libraries will special-case 
situations where exact results are expected.

> 2014-03-04 15:43 GMT+04:00 Dio Darkclainer :
>
>     Hello all!
>     Code:
>
>     for i=1,20 do
>         if math.floor(math.log(2^i,2)) ~= i then
>            print(i)
>         end
>     end
>
>     will be output
>     3
>     6
>     12
>     13
>
>     if use math.log(2^i)/math.log(2) intstead all work correctly
>     lua 5.2.3


--
Cheers,
Kein-Hong Man (esq.)
Kuala Lumpur, Malaysia