function FermatTest(n, k)
% y = FermatTest(n, k)
% Input: an integer n > 3, and an optional second input k, a positive integer.
% Default value for k: 1
% The program will apply the Fermat primality test (Algorithm 8.2) k times.
% Output: y will be 1 if at least one of the k tests has found n to be
% composite, and 0 in case all of the tests were inconclusive (meaning,
% informally, they all found n to be probably prime).
% Program accepts symbolic inputs and calls on the FastExpSym program.
y = 0; %At the end, y will be 1 if at least one of the k tests has found n to be
% composite, and 0 in case all of the tests were inconclusive (meaning,
% informally, they all found n to be probably prime).
if nargin < 2, k = 1; end
for test = 1:k
a = ceil((n-3)*rand)+1; %randomly select a base a: 1