%computes the BER
%inputs/outputs
%inputs: a_vec (binary 0/1 original data), ahat (binary 0/1 output data),
% num_bits -- size of vectors
%output: out -- computed BER

function [out] = ber_compute(a_vec, ahat, num_bits)

    ber=0;
    for ii=3:num_bits; % first 2 bits avoided in BER computation
        if(a_vec(ii)~=ahat(ii)) 
            ber=ber+1;
        end
    end
    out = ber/(num_bits-2);