Re: incorrect test on gamma function ?

[Tatsuro MATSUOKA]

Hello

On cygwin, are gamma and lgamma on the GCC used or slatec gamma used?

On MinGW, slatec gamma is used and I have sent a patch for slatec gamma 
function. 

bug #30824: gammaln(0) and gammaln((minus integer)) give slatec error
http://savannah.gnu.org/bugs/?func=detailitem&item_id=30824

If this modification is incorrect, please give consider the patch.

Regards

Tatsuro
--- Marco Atzeri  wrote:

> Hi,
> could someone explain me why
> we expect:
> 
> gamma(0) = Inf 
> gamma(-1) = NaN 
> 
> >>>>> processing /pub/hg/octave/src/mappers.cc
>   ***** test
>  x = [-1, 0, 1, Inf];
>  v = [NaN, Inf, 1, Inf];
>  assert (gamma(x), v);
>  assert (gamma(single (x)), single (v));
> !!!!! test failed
> assert (gamma (x),v) expected
>    NaN   Inf     1   Inf
> but got
>    Inf   Inf     1   Inf
> NaNs don't match
> 
> considering the graphics
> http://en.wikipedia.org/wiki/Gamma_function
> 
> I presume the two values should be both Inf (or both NaN)
> 
> Marco
> 
> 
> 
>       
> 
> 


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