Re: [Help-gsl] Fwd: Modifying adaptive integration function

[Francesco Florian]

On Thursday, May 10, 2018 8:17:47 PM CEST lostbits wrote:
> 
> On 5/10/2018 8:08 AM, Patrick Alken wrote:
> > On 05/10/2018 04:18 AM, Francesco Florian wrote:
> >> Hello!
> >> Since I have received no answer, I wonder whether this is the right 
> >> mailing list for this question. If it is not, can you please point me 
> >> to the right one?
> >> Thank you
> >
> > Hello,
> >
> >   What exactly are you trying to do that QAG cannot? Perhaps there is 
> > an alternate way without rewriting the function. My guess is you could 
> > get away with just removing the GSL_COERCE_DBL wrappers from the code, 
> > but it may not match the original QUADPACK results, according to the 
> > comments in qag.c.
> >
> > Patrick
> >
> My guess is that gcc -DHAVE_EXTENDED_PRECISION_REGISTERS ... would 
> define the pre-process variable, if that's what you want. If you do 
> nothing then the variable is not defined. More to the point:
> 
> #if HAVE_EXTENDED_PRECISION_REGISTERS
> #define GSL_COERCE_DBL(x) (gsl_coerce_double(x))  // used with gcc 
> --DHAVE_EXTENDED_PRECISION_REGISTERS
> #else
> #define GSL_COERCE_DBL(x) (x)  // used without defining the variable
> #endif

I was looking for a way to check if the compiler actually supports it. The 
method above seems to rely on me knowing that, and then passing 
-DHAVE_EXTENDED_PRECISION_REGISTERS to gcc if appropriate.
Patrick Alken's answer seems to suggest it is ok not to match QUADPACK results; 
if it is correct it would work for me.

-- 
Francesco Florian