The initial question was: what is the minimum needed to gain practical control over the zeta function across the full complex plane, for s ∈ ℂ (including Re(s) < 1 and Re(s) < 0)?
This project is one possible answer. It provides two JavaScript functions, vanilla_zeta() and vanilla_gamma(), aimed at computing the complex zeta and gamma functions with a very simple JS implementation.
You can try both functions directly in the browser via the linked calculator at: www.zeta-calculator.com
Show HN: Complex ζ(s) and Γ(s) in pure JavaScript (works for Re(s)<0) | Heykuki News