Important note: this article is outdated! Go to http://zsiciarz.github.io/24daysofrust/ for a recent version of all of 24 days of Rust articles. The blogpost here is kept as it is for historical reasons.

τ (tau) is one of the most important mathematical constants (if not the most important), relating circle's circumference to it's radius. See the tau manifesto for the long explanation if you're still an unbeliever. Can we use it in Rust? Of course, there's a crate for that!