Write a function out $=$ polydiff $(C,x)$ which finds the derivative of a polynomial of degree length $($C$)-1$ with the coefficients given in the row$/$column vector C evaluated at $x.$ Your function should output a suitable error message if $C$ is not a row or column vector. Your function should also plot the polynomial over the interval $x-1,x+1.$ Test your function for $C=$repmat$(myvec(1$:$3),1,2)$ and $x=$myvec$(2).$