I<gcc> supports long doubles (12 bytes). However, several additional
long double math functions are necessary to use them within Perl
-(I<{atan2,cos,exp,floor,fmod,frexp,isnan,log,modf,pow,sin,sqrt}l,strtold>).
+(I<{atan2, cos, exp, floor, fmod, frexp, isnan, log, modf, pow, sin, sqrt}l,
+strtold>).
These are B<not> yet available with Cygwin.
=item * C<-Dusethreads>