The story
Named after mathematician Srinivasa Ramanujan.
Etymology from Wiktionary, CC BY-SA 4.0.
Ramanujan theta function
Today it means: A theta function that generalizes the form of the Jacobi theta functions while capturing their general properties. It is defined as: f(a,b)=∑_(n=-∞) ᪲a^( frac )n(n+1)2;b^( frac )n(n-1)2 for |ab| < 1. Full definition →