I'm pleased to announce that I've uploaded the *besout* package to hackage. http://hackage.haskell.org/package/besout *besout* is intended to compute extended gcd of polynomials over F_p[x]. The three main functions of *besout* are : *multPolyZ* : product of two polynomial P , Q in F_p[x] using a technique similar to Horner rules. *euclidanPolyMod* : quotient and remainder of euclidean division of polynomial P by Q in the ring F_p[x] where p is a prime number. *extendedgcdpoly* : extended gcd of polynomials P and Q in the ring F_p[x] where p is a prime number. I am open to suggestions. Abdelwaheb Miled