This is a rather vague question, and I apologize in advance if this is considered offtopic. I remember reading this great blog article by someone (quite possibly by Dr. Chris Rackauckas) about using custom types with DifferentialEquations.jl. It showed off impressive capabilities of the package to use things like
BigRational and arbitrary precision floating point numbers. it also talked about how to turn off some flags so that you can use rational numbers. Unfortunately, I am unable to locate the blog post anymore, and would really love to read it again. Does anybody happen to know of the blog?