 Usage:  {edr, eigen} = sir (x, y, h)  
 
 Input:

  x                      n x p matrix, the explonatory variable 
                         
  y                      n vector, the dependent variable 
                         
  h                      scalar, number of slices (h>=2) 
                         width of slice (0 < h < 1) 
                         elements in a slice (-h) 
                         
 Output:

  edr                    p x p matrix containing estimates of the edr 
                         
  eigen                  p vector of the eigenvalues 
                         
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(C) MD*TECH Method and Data Technologies, 17.8.2000
