Hello, I would like to convert this mathematical equation into MATLAB code.

[John D'Errico]

You already got a valid answer. There is no reason to then post the same question a second time. I closed the other.

Answer 1

[Bora Eryilmaz]

x = rand(100,1);
N = numel(x);

num = (sum(x)/N)^2;
den = sum(abs(x.^2)) / N;

s = num / den

s = 0.7726

[Walter Roberson]

x_m = rand(100,1);

%Bora's version, valid only for reals
N = numel(x_m);
num = (sum(x_m)/N)^2;
den = sum(abs(x_m.^2)) / N;
s = num / den

s = 0.7135

%a more compact version valid only for reals
num2 = mean(x_m).^2;
den2 = mean(x_m.^2);
s2 = num2/den2

s2 = 0.7135

%analog for compact version but valid for complex as well
num3 = abs(mean(x_m)).^2;
den3 = mean(abs(x_m).^2);
s3 = num3 / den3

s3 = 0.7135

What you can get away with depends on whether there might be complex numbers involved.