C fmod function

C fmod function

[Candida Ferreira]

Hi everyone,

Is there in Ada a built-in function equivalent to the fmod function in C++?

Many thanks.

Candida

---
Candida Ferreira, Ph.D.
Chief Scientist, Gepsoft
http://www.gene-expression-programming.com/author.asp

GEP: Mathematical Modeling by an Artificial Intelligence
(Springer Verlag edition 2006)
http://www.gene-expression-programming.com/Books/index.asp
Online Version:
http://www.gene-expression-programming.com/GepBook/Introduction.htm

Modeling Software:
http://www.gepsoft.com/

Re: C fmod function

[Dmitry A. Kazakov]

On Wed, 12 Apr 2006 14:10:28 GMT, Candida Ferreira wrote:

> Is there in Ada a built-in function equivalent to the fmod function in C++?

Yes. See Annex A.5.3, Remainder attribute defined for floating-point types.  

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de

Re: C fmod function

[Candida Ferreira]

Dmitry A. Kazakov wrote:
>> Is there in Ada a built-in function equivalent to the fmod function in 
>> C++?
>
> Yes. See Annex A.5.3, Remainder attribute defined for floating-point 
> types.

Thanks, Dmitry. I was aware of the Remainder attribute, but having read the 
definition I wasn't sure if it corresponded exactly to the C++ fmod function 
which can be represented by the generic expression fMod(x,y) = ((x / y) - 
(Sign(x / y) * Floor(Abs(x / y)))) * y.

Best wishes,
Candida

---
Candida Ferreira, Ph.D.
Chief Scientist, Gepsoft
http://www.gene-expression-programming.com/author.asp

GEP: Mathematical Modeling by an Artificial Intelligence
(Springer Verlag edition 2006)
http://www.gene-expression-programming.com/Books/index.asp
Online Version:
http://www.gene-expression-programming.com/GepBook/Introduction.htm

Modeling Software:
http://www.gepsoft.com/

Re: C fmod function

[Dmitry A. Kazakov]

On Wed, 12 Apr 2006 15:49:36 GMT, Candida Ferreira wrote:

> Dmitry A. Kazakov wrote:
>>> Is there in Ada a built-in function equivalent to the fmod function in 
>>> C++?
>>
>> Yes. See Annex A.5.3, Remainder attribute defined for floating-point 
>> types.
> 
> Thanks, Dmitry. I was aware of the Remainder attribute, but having read the 
> definition I wasn't sure if it corresponded exactly to the C++ fmod function 
> which can be represented by the generic expression fMod(x,y) = ((x / y) - 
> (Sign(x / y) * Floor(Abs(x / y)))) * y.

Yes, you are right. The above rounds towards zero and the result has the
sign of x. Ada's remainder rounds to the nearest number, so the sign can be
any and the result's absolute value is no greater than |y/2|.

You can convert it to fmod as follows:

f := S'Remainder (x, y);
if Sign (x) = Sign (f) then
   return f;
elsif Sign (y) = Sign (f) then
   return f - y;
else
   return f + y;
end if;

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de

Re: C fmod function

[Candida Ferreira]

I was finally able to test it and Ada's Remainder is not the same as C++ 
fmod. C++ fmod can be expressed by the generic form fMod(x,y) = ((x / y) - 
(Sign(x / y) * Floor(Abs(x / y)))) * y.

Candida


"Candida Ferreira" <cferreira@seehomepage.com> wrote in message 
news:kk9%f.233449$zk4.160702@fe3.news.blueyonder.co.uk...
> Dmitry A. Kazakov wrote:
>>> Is there in Ada a built-in function equivalent to the fmod function in 
>>> C++?
>>
>> Yes. See Annex A.5.3, Remainder attribute defined for floating-point 
>> types.
>
> Thanks, Dmitry. I was aware of the Remainder attribute, but having read 
> the definition I wasn't sure if it corresponded exactly to the C++ fmod 
> function which can be represented by the generic expression fMod(x,y) = 
> ((x / y) - (Sign(x / y) * Floor(Abs(x / y)))) * y.
>
> Best wishes,
> Candida
>
> ---
> Candida Ferreira, Ph.D.
> Chief Scientist, Gepsoft
> http://www.gene-expression-programming.com/author.asp
>
> GEP: Mathematical Modeling by an Artificial Intelligence
> (Springer Verlag edition 2006)
> http://www.gene-expression-programming.com/Books/index.asp
> Online Version:
> http://www.gene-expression-programming.com/GepBook/Introduction.htm
>
> Modeling Software:
> http://www.gepsoft.com/
>
> 

Re: C fmod function

[Candida Ferreira]

I was finally able to test it and Ada's Remainder is not the same as C++ 
fmod. C++ fmod can be expressed by the generic form fMod(x,y) = ((x / y) - 
(Sign(x / y) * Floor(Abs(x / y)))) * y.

Candida

"Candida Ferreira" <cferreira@seehomepage.com> wrote in message 
news:kk9%f.233449$zk4.160702@fe3.news.blueyonder.co.uk...
> Dmitry A. Kazakov wrote:
>>> Is there in Ada a built-in function equivalent to the fmod function in 
>>> C++?
>>
>> Yes. See Annex A.5.3, Remainder attribute defined for floating-point 
>> types.
>
> Thanks, Dmitry. I was aware of the Remainder attribute, but having read 
> the definition I wasn't sure if it corresponded exactly to the C++ fmod 
> function which can be represented by the generic expression fMod(x,y) = 
> ((x / y) - (Sign(x / y) * Floor(Abs(x / y)))) * y.
>
> Best wishes,
> Candida
>
> ---
> Candida Ferreira, Ph.D.
> Chief Scientist, Gepsoft
> http://www.gene-expression-programming.com/author.asp
>
> GEP: Mathematical Modeling by an Artificial Intelligence
> (Springer Verlag edition 2006)
> http://www.gene-expression-programming.com/Books/index.asp
> Online Version:
> http://www.gene-expression-programming.com/GepBook/Introduction.htm
>
> Modeling Software:
> http://www.gepsoft.com/
>
>