The Gamma function.

[Richard B. Kreckel]

Hi folks,

I have just checked with Martin v. Löwis about that issue.  Martin is
quite C-standard-literal.  The question arouse how to call the (already
present) Gamma function in GiNaC once and for all.  The standard ISO/IEC
9899:1999, frequently dubbed as C99, states:

> 7.12.8.3 The lgamma functions
> Synopsis
>    #include <math.h>
>    double lgamma(double x); 
>    float lgammaf(float x);
>    long double lgammal(long double x);
> 
> Description
> 
> The lgamma functions compute the natural logarithm of the absolute
> value of gamma of x: log-e | G(x) |. A range error occurs if x is too
> large or if x is a negative.
> 
> Returns
> 
> The lgamma functions return the value of the natural logarithm of the
> absolute value of gamma of x.
> 
> 7.12.8.4 The tgamma functions
> 
> Synopsis
>   #include <math.h>
>   double tgamma(double x);
>   float tgammaf(float x);
>   long double tgammal(long double x);
> 
> Description
> 
>   The tgamma functions compute the gamma function of x: G(x). A domain
>   error occurs if x is a negative integer or zero. A range error may
>   occur if the magnitude of x is too large or too small.
> 
> Returns
> 
> The tgamma functions return the gamma function value.

The next revision of ISO/IEC 14882:1998 (the C++ standard) will follow
this definition from the C standard.  Since it is kind of a policy not to
work against the language C++ I vote for forgetting about esthetic 
qualms and adopting this behaviour and call it ex tgamma(ex) in GiNaC
0.x.y | x>5.  A function ex lgamma(ex) may be introduced as well to make
the distinction clear.

Any serious objections?
                    -richy.
-- 
Richard Kreckel
<Richard.Kreckel at Uni-Mainz.DE>
<http://wwwthep.physik.uni-mainz.de/~kreckel/>