MPFRCX is a library for the arithmetic of univariate polynomials over arbitrary precision real (MPFR) or complex (MPC) numbers, without control on the rounding. The functions implemented are not very numerous and somewhat idiosyncratic: the main motivation behind the library is to have functionality available for the floating point approach to complex multiplication. However, asymptotically fast routines such as Toom–Cook and the FFT for multiplication of polynomials are available, as well as fast routines for interpolation and evaluation based on trees of polynomials.