 Usage:  pc = pca (x)  
 
 Input:

  x                      n x p matrix 
                         
 Output:

  pc.y                   n x p matrix principal components 
                         
  pc.gamma               p x p matrix of eigenvectors 
                         
  pc.lambda              p x 1 matrix of eigenvalues 
                         
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(C) MD*TECH Method and Data Technologies, 17.8.2000
