Function to compute Scallop Loss

Question

I want to make a function that computes the value of the Scallop loss for a Rectangular, Hamming and Blackman window using the Scallop loss formula. I have created a function but it only returns that answer 0, have I made an error?

function s_l = scallop loss(len)
window = rectwin(len);
num_total = 0;
den_total = 0;

for n = 0:len-1
    A1 = exp(-((1i*(n)*pi)/len));
    A2 = window(n+1)*A1;
    num = abs(A2);
    den = win(n+1);
    num_total = num_total + num;
    den_total = den_total + den:
end

result = 20*log(num_total/den_total);

s_l = result;

Answer 1

You have a maths problem:

abs(sum(A)) != sum(abs(A))

They are not the same!

Change your code to:

window = rectwin(len);
num_total = 0;
den_total = 0;

for n = 0:len-1
    A1 = exp(-((1i*(n)*pi)/len));
    A2 = window(n+1)*A1;
    num = A2;                      % !!
    den = abs(window(n+1));        % you also forgot the abs  here
    num_total = num_total + num;
    den_total = den_total + den;
end
num_total=abs(num_total);    % !!
result = 20*log(num_total/den_total);

s_l = result;