[Help-gsl] Fwd: Modifying adaptive integration function

[Francesco Florian]

Hello,
I'm currently trying to write a modified version of the functions in 
integration/qag.c to solve a problem I have, but I ran into this problem:
qag uses the `GSL_COERCE_DBL' macro, which is defined in configure.ac (the 
relevant code follows)

#if HAVE_EXTENDED_PRECISION_REGISTERS
#define GSL_COERCE_DBL(x) (gsl_coerce_double(x))
#else
#define GSL_COERCE_DBL(x) (x)
#endif

How should I test my compiler (GCC) to get the right version to use?

Moreover, I noticed that `retrieve (workspace, &a_i, &b_i, &r_i, &e_i);' is 
called at both the beginning and the end of the `do.., while' iteration (lines 
181 and 231), and the second call seems useless. Is that correct?
Thank you