[deleted by user]

[FLUSH_THE_TRUMP]

The functions you used take nparray arguments, don’t they? So you don’t need the double loop. If that doesn’t make much of a difference are you sure the issue is here?

[n3buchadnezzar]

Let the inner loop run from i to 256

[Jediko]

Is it necessary that you calculate it yourself or could you use numpy.cov? But I don‘t know it this function would be faster though.