Hello, I've got quick questions. 1. When I have a matrix, x, and try to get different values for each x (given y = (x^2)+b), I get this error. ??? Error using ==> mpower Matrix must be square. 2. x is [1x101] double according to MATLAB and I've had this problem when I was taking derivative as well. I've lost numbers throughout the derivative, which i understands. so x' = [1x100] and x'' = [1x99] and so forth. What's the best way to solve these problems. Thank you.