Usage: 
mh = lpderest (x, h {,q {,p {,K} {,d}}})

Input: 
 x  n x 2, the data. In the first column the
independent, in the second column the
dependent variable.

 h  scalar, bandwidth. If not given, the rule of thumb
bandwidth computed by lpderrot is used.

 q  integer <=4, order of derivative. If not
given, q=1 (first derivative) is used.

 p  integer, order of polynomial. If not given,
p=q+1 is used.

 K  string, kernel function on [1,1] or Gaussian
kernel "gau". If not given, the Quartic kernel
"qua" is used.

 d  scalar, discretization binwidth. d must be smaller
than h. If not given, the minimum of h/3 and
(max(x[,1])min(x[,1]))/100 is used.

Output: 
 mh  m x 2 matrix, the first column is a grid and the
second column contains the derivative estimate on
that grid. 