 Usage:  res = plmk(x,t,y,h)  
 
 Input:

  x                      n x p matrix, the design 
                         
  t                      n x 1 matrix, the design in [0, 1] 
                         
  y                      n x 1 matrix, the response 
                         
  h                      p x 1 matrix or scalar, chosen bandwidth 
                         
 Output:

  res.hbeta              p x 1 matrix, estimate of parameter 
                         
  res.hsigma             scalar, estimate of variance 
                         
  res.hg                 n x 1 matrix, estimate of nonparameter function 
                         
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(C) MD*TECH Method and Data Technologies, 17.8.2000
