Legendre, Jacobi and Kronecker Symbol Computation
The three quadratic symbols, their differing meanings, and the reciprocity-based algorithm that computes them without factoring.
Every page in the KEVOS library tagged Quadratic Residue. 6 pages.
The three quadratic symbols, their differing meanings, and the reciprocity-based algorithm that computes them without factoring.
Choosing the factor base for the quadratic sieve, the quadratic residue criterion, and the multiplier.
Extracting square roots modulo a prime: the easy congruence classes, the general Shanks-Tonelli algorithm, and lifting to prime powers.
CFRAC: generating small quadratic residues from the continued fraction expansion, and the congruence-of-squares framework it established.
Quadratic residues, Euler's criterion, the Legendre symbol, its Jacobi and Kronecker extensions, and the reciprocity-based algorithm that evaluates them in logarithmic time.
Computing modular square roots: the p ≡ 3 (mod 4) shortcut, the Tonelli–Shanks algorithm and its 2-adic structure, and Cornacchia's algorithm for x² + dy² = p.