John Maddock:
Integer Types ~~~~~~~~~ 1/ GMP (MPZ). 2/ libtommath.
Rational Types ~~~~~~~~~~ 1/ GMP (MPQ). [ But note that the integer types can also be used as template aruments to Boost.Rational ]
Floating Point Types ~~~~~~~~~~~~~~ 1/ GMP (MPF) 2/ MPFR 3/ cpp_float - an all C++ Boost-licensed backend based on Christopher Kormanyos' e_float code. [ Note these three types are fully compatible with Boost.Math Trunk - so you get full standard library plus special function support ]
Jarrad Waterloo:
It would be nice in the future to also have "all C++ Boost-licensed backend" options for the "Integer Types" and "Rational Types"
I love what John has done with this concept. I am already way behind on a proposal for boost::multiprecision which includes the boost-licensed floating-point backend. I just need to find a few days to complete the documentation. You can find boost::multiprecision in the sandbox. Best regards, Chris.