- modular-inverse a nprocedure
- a
- integer
- b
- integer
Returns the inverse of a modulo n if a and n are coprime, otherwise raises an error. The modulus n must be positive, and a must be nonzero.
Formally, if a and n are coprime, b = (modular-inverse a n) is the unique natural number less than n such that (* a b) = 1 (mod n).
> (modular-inverse 2 5) 3 > (modulo (* 2 3) 5) 1
Wikipedia: Multiplicative Inverse