function [signal_out] = isi(signal_in,delay_1,delay_2)

if delay_1 > delay_2
    temp = delay_1;
    delay_1 = delay_2;
    delay_2 = temp;
end

if delay_1 == 0 & delay_2 == 0
   signal_out = signal_in;
   return
end

signal_1 = signal_in;

len = length(signal_in);

new_len = len + delay_2;

signal_1(new_len) = 0;
signal_2 = zeros(1,new_len);
signal_3 = zeros(1,new_len);

signal_2(delay_1 + 1:delay_1 + len) = signal_in;
signal_3(delay_2 + 1:delay_2 + len) = signal_in;

%for k = 1:len,
   %signal_2(k + delay_1) = signal_1(k);
   %signal_3(k + delay_2) = signal_1(k);
%end

signal_out = signal_1 + signal_2 + signal_3;