Re: Lua5 / poor performance

["Wim Couwenberg" <w.couwenberg@...>]

Hi,

Peter S. Housel:
> A more portable, and very fast, method of hashing floating-point numbers
> might be:
>
> 1) Extract the manitssa and exponent using frexp() function.
> 2) Multiply the mantissa by (double) 2^(bits in a long - 1)
> 3) Truncate the multiplication result to a long
> 4) Hash this result with together with the exponent

My thoughts exactly!  I was wondering if replacing the multiply by an ldexp
call could perhaps be quicker?  You can also "shift out" enough parts of the
mantissa to exhaust its precision (to avoid collisions for values that are
very close.)

Bye,
Wim