best way to get mantissa from mpf_t

[Patrick Pelissier]

> Seriously, I will rename some fields in 4.3, with the hope that I get
> feedback from those who depend on internals, since such usages suggest
> weaknesses of GMP's interface.  I'd like to address those weaknesses.

 In general, the applications do it because they need an interface similar too:
http://www.mpfr.org/mpfr-current/mpfr.html#Custom-Interface

--
 Patrick Pélissier