 Usage:  d = dwade(x,y,h)  
 
 Input:

  x                      n x d matrix , the observed explanatory variable 
                         
  y                      n x 1 matrix , the observed response variable 
                         
  h                      d x 1 or 1 x 1 matrix , chosen bandwidth 
                         
 Output:

  d                      d x 1 matrix, the density weighted average 
                         derivative estimator 
                         
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(C) MD*TECH Method and Data Technologies, 17.8.2000
