 Usage:  pv = sptest(x,y,p{,levels})  
 
 Input:

  x                      n x p matrix , the observed explanatory variable 
                         where the discrete variables have to be placed 
                         into the last (dis) columns 
                         
  y                      n x 1 matrix , the observed response variable 
                         
  p                      scalar , the polynomial degree of the Hypothesis 
                         
  levels                 dis x 1 vector of integrers < 4, 
                         wavelet levels for the components 
                         of the discrete variables; max = 3 
                         
 Output:

  pv                     p-value of the hypothesis 
                         
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(C) MD*TECH Method and Data Technologies, 17.8.2000
