Integer Factoring

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Zach Kost-Smith <>


LLGPL ( except for the file "ulimyhmpqs-1.0.lisp" which is 3 Clause BSD, LLGPL (


This library presents a set of algorithms for computing integer factorizations. An interface is provided that takes an integer and will return a list of prime numbers such that, when multiplied together, will result in the original number.

There is no magic sauce here or mathematical breakthroughs; the time complexities of each algorithm is exponential.


The library provides the function factor.

Specific factoring methods can be accessed from the package cl-factoring-algorithms.

1.2General Purpose Factoring Algorithms

  1. Trial Division
  2. Pollard's Rho
  3. Brent's Cycle
  4. Hypercubic Polynomial Quadratic Sieve


This library is licensed under the LLGPL where possible.

Certain algorithms may be developed by others and be licensed under more permissive licenses. If development is performed on these, the license will remain as is (the LLGPL won't infect them).

Dependencies (3)

  • cl-primality
  • iterate
  • stefil

Dependents (0)

    • GitHub
    • Quicklisp