ARPREC is a software package for performing arbitrary precision arithmetic. It consists of a revision and extension of Bailey's earlier MPFUN package, enhanced with special IEEE numerical techniques.

This package supports a flexible, arbitrarily high level of numeric precision -- the equivalent of hundreds or even thousands of decimal digits (up to approximately ten million digits if needed). Special routines are provided for extra-high precision (above 1000 digits). The entire library is written in C++. High-precision real, integer and complex datatypes are supported.