This doesn't make sense on multiple levels. You want a 1x100 vector, but your loop only iterates 10 times, and it only attempts a single assignment which is completely independent of the loop. The loop serves no purpose.
The error is because the RHS of the assignment is a scalar, but the LHS is a vector that never changes.
% y(100) % is a scalar
% this is a 2-element vector
atan([-1.74908051612442,0.591783255482434])*180/pi
Maybe you meant to use atan2() or atan2d()?
... but the loop still doesn't make sense, since nothing changes.
