 Usage:  y = eigensm (x)  
 
 Input:

  x                      array, p x p x d1 x d2 x ... x dn, 
                         symmetric in each layer. 
                         
 Output:

  y.values               array, p x 1 x d1 x d2 x ... x dn, 
                         the eigenvalues. 
                         
  y.vectors              array, p x p x d1 x d2 x ... x dn, 
                         the normalized eigenvectors. 
                         
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(C) MD*TECH Method and Data Technologies, 17.8.2000
