On platforms that don't have a native implementation of log1p, GSL
substitutes gsl_log1p.
But in many files where log1p is used, the gsl_sys.h header (where gsl_log1p
is declared) is not included so the compiler doesn't pick up the declaration
of gsl_log1p and hence wrongly concludes that it returns an int.
So the header gsl_sys.h needs to be included in all files where log_1p is
used.
This also applies to other functions that seek to substitute for missing
'standard' functions.
I picked this up on the Microsoft compiler but it also impacts on the Intel
compiler on Windows.
best regards,
Brian Gladman
