 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. 
                         
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(C) MD*TECH Method and Data Technologies, 17.8.2000
