Re[2]: MAD 0.15 Accuracy

Hello Rob,

Yes you are right. I have switched to FPM_INTEL and result is good.
In past I used FPM_DEFAULT.
ok - series of new tests are coming.
and any way 16 bit - give me only limited accuracy - but calculation
is very efficient ...
So I going to make two modes: 16 bits calculation and 32 bit for gourmands :).

Thank You for answer.



Thursday, December 4, 2003, 12:26:21 AM, you wrote:
RL> 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?

RL> Yes.

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

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

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




-- 
Best regards,
 Grigory                            mailto:[email protected]