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MPFR is a portable library written in C for arbitrary precision arithmetic
on floating-point numbers. It is based on the GNU MP library.
It aims to extend the class of floating-point numbers provided by the
GNU MP library by a precise semantics. The main differences
with the mpf
class from GNU MP are:
mpfr
code is portable, i.e. the result of any operation
does not depend (or should not) on the machine word size
mp_bits_per_limb
(32 or 64 on most machines);
mpfr
provides the four rounding modes from the IEEE 754-1985
standard.
In particular, with a precision of 53 bits, mpfr
should be able
to exactly reproduce all computations with double-precision machine
floating-point
numbers (double
type in C), except the default exponent range
is much wider and subnormal numbers are not implemented but can be emulated.
This version of MPFR is released under the GNU Lesser General Public License. It is permitted to link MPFR to non-free programs, as long as when distributing them the MPFR source code and a means to re-link with a modified MPFR library is provided.
Everyone should read MPFR Basics. If you need to install the library yourself, you need to read Installing MPFR, too.
The rest of the manual can be used for later reference, although it is probably a good idea to glance through it.