index must be a positive integer or logical. error in matlab

n = 2;

m=2*(n-1)+1;

theta=pi/m;

for i=1:n

 y(i) = cos((1-i+(m-1)/2)*theta);

 y(i-1)=cos((1-(i-1)+(m-1)/2)*theta); < --- line error

end

How could I rewrite this code to be able to get the y-1 matrix

Answer 1

[Roger Stafford]

You will have to rethink how your y vector is to be indexed. It cannot accept index values of zero which you have used here: when i is equal to 1 you would be indexing y(i-1) as y(0).

[Jonathan Guarneros]

I am having trouble rewriting my code to satisfy the conditions i want