strip a matrix
[z]=trimr(x,n1,n2)
x = input matrix (or vector) (n x k)
n1 = first n1 rows to strip
n2 = last n2 rows to strip
z = x(n1+1:n-n2,:)
trimr([1:10]',2,3) // returns: //! 3. ! //! 4. ! //! 5. ! //! 6. ! //! 7. !