John D. Cook • 2/15/2026

Wagon’s algorithm in Python

This article provides a step-by-step implementation of Stan Wagon's algorithm in Python to find integer solutions for x² + y² = p, where p is a large odd prime. It covers finding a quadratic non-residue modulo p, computing a square root of -1 mod p, and applying a modified Euclidean algorithm with a precision-aware stopping condition using Python's isqrt. The tutorial includes complete code and demonstrates the solution for a 255-bit prime.

0 comments

#Python #algorithm #number theory