The MPFR library is a C library for multiple-precision floating-point
computations with exact rounding (also called correct rounding).
It is based on the GMP multiple-precision library.

The main goal of MPFR is to provide a library for multiple-precision
floating-point computation which is both efficient and has well-defined
semantics. It copies the good ideas from the ANSI/IEEE-754 standard
for double-precision floating-point arithmetic (53-bit mantissa).