libcln6 binary package in Ubuntu Xenial amd64

 CLN is a library for computations with all kinds of numbers. It has a
 rich set of number classes, including integers (with unlimited precision),
 reals with various precisions (including unlimited), rationals, complex
 numbers and polynomials. The kernel is written in assembly language.
 It uses garbage collection (automatic, without imposing any burden on the
 main application). Many efficient algorithms (i.e. for all transcendental
 functions) are implemented.

Source package