gcd1818

gcd1818 is a software project and library that focuses on computing the greatest common divisor (GCD) of integers and on related number-theoretic algorithms. The project publishes reference implementations and a set of benchmarks intended for use in education, research, and performance testing. While the exact origins are informal, gcd1818 began as a community effort in 2018, drawing participation from developers interested in efficient gcd computations and algorithmic optimization.

Technical scope includes core gcd routines implementing the classic Euclidean algorithm, the binary GCD (Stein's) algorithm, and optimizations such as Lehmer's trick for large integers. The library aims to cover both fixed-width integers and arbitrary-precision arithmetic by interfacing with existing big integer libraries. It provides language bindings for common languages (for example C, C++, Rust, and Python) to facilitate integration into other projects.

gcd1818 is used in educational contexts to illustrate algorithmic trade-offs and in practical performance testing for numeric libraries. Its benchmarks compare variants of gcd implementations across input sizes, highlighting cases where certain strategies outperform others.

Community governance and contribution guidelines emphasize openness, code quality, and thorough testing. The project maintains documentation describing algorithms, correctness proofs, and usage examples.

See also: Euclidean algorithm, Binary GCD, Lehmer's algorithm, number theory software.