Modular Inverse

Finds the modular inverse over finite (Galois) field.

MULINV(X,P) is a function that finds the modular inverse of vector X over finite (Galois) field of order P, i.e. if Y = MULINV(X,P)
then (X*Y) mod P = 1 or Y = X^(-1) over field of order P.

The input parameters are vector of integers X and a scalar P which represents the field order. The output is a size(X) vector which
is the modular inverses of X over P.

The field order P must be a prime number and all elements of X should belong to the field i.e. X < P. Note: Over any field of numbers
the modular inverse of one is one and the modular inverse of zero doesn't exist.

Example: X = [1 2 5], P = 7.
Y = MULINV(X,P) => Y = [1 4 3];

The function doesn't check the format of input parameters.

Reference:
S. Bruce, Applied Cryptography: Protocols, Algorithms, and Source Code in C, 2nd edition, John Wiley and Sons, Inc., US-Canada, 1996.