FLINT is a C library for doing number theory, maintained by William Hart.

FLINT supports arithmetic with numbers, polynomials, power series and matrices
over many base rings, including:
* Multiprecision integers and rationals
* Integers modulo n
* p-adic numbers
* Finite fields (prime and non-prime order)
* Real and complex numbers (via the Arb extension library)

WWW: http://www.flintlib.org/