Re: MAD 0.15 Accuracy

On Dec 2, 2003, at 11:00 PM, Grigory A. wrote:
> I tested my implementation of some math function for MAD 0.15 library.
> And I have found this:
>
> function
> mad_fixed_t III_requantize(unsigned int value, signed int exp)
> in layer3.c file
>
> input
> value=8
> exp=-23;
>
> that means
> 8^(4/3)*2(-5.75)
> correct?

Yes.

> result obtained by
> mad_f_todouble(requantized)is
>
> 0.297241
>
> but calculator says
>>> 8^(4/3)*2^(-5.75)
> ans = 0.29730177875068

Which fixed-point math (FPM_* define) and optimization (OPT_*) settings 
are you using?

For FPM_INTEL with default optimization, I find III_requantize(8, -23) 
returns 0x04c1bf82 (0.29730177670717239).

-- 
Rob Leslie
[email protected]