Chapter 26 The num library: arbitrary-precision rational arithmetic

The num library implements integer arithmetic and rationalarithmetic in arbitrary precision. It was split off the coreOCaml distribution starting with the 4.06.0 release, and can now be foundat https://github.com/ocaml/num.

New applications that need arbitrary-precision arithmetic should use theZarith library (https://github.com/ocaml/Zarith) instead of the Numlibrary, and older applications that already use Num are encouraged toswitch to Zarith. Zarith delivers much better performance than Numand has a nicer API.