Ch GMP
The Ch GMP package is a Ch interface to the GNU Multiple Precision Arithmetic Library (GMP). GMP is a free library for arbitrary precision arithmetic, operating on signed integers, rational numbers, and floating point numbers. There is no practical limit to the precision except the ones implied by the available memory in the machine GMP runs on. GMP has a rich set of functions, and the functions have a regular interface. With the Ch GMP package, all C (or C++) programs using functions from the GMP C library can readily run in Ch interpretively without compilation.
Ch GMP is an ideal solution for cryptography applications and research,
Internet security applications, algebra systems, computational algebra
research, teaching and learning, etc.
Release Notes
Ch GMP version 1.0, May 31, 2005
System Requirements
(1) Ch Standard or Professional Edition version 5.0.1.12251
or higher for Windows or Linux.
Ch is free and available for multiple platforms from SoftIntegration at http://www.softintegration.com. 

(2) The GNU Multiple Precision Arithmetic Library version 4.1.4. 