MATLAB: What code could possibly solve this problem

Question

Answer 1

You need to put a closed bracket at the end ')' in the last term.

yy.data(:,4) * (yy.data(:,4))

But I suspect, there will be error in multiplication. You need to use

yy.data(:,4) .* yy.data(:,4)

Or

yy.data(:,4).^2