Determine the Projection Coefficients
q The EOF analysis asks that the projection coefficients are determined in
such a way that:
     (1) z1 explains the maximum possible amount of the variance of the x’s;
     (2) z2 explains the maximum possible amount of the remaining  variance
          of the x’s;
     (3) so forth for the remaining z’s.
q With these requirements, it can be shown mathematically that the
projection coefficient functions (eij) are the eigenvectors of the covariance
matrix of x’s.
q The fraction of the total variance explained by a particular eigenvector is
equal to the ratio of that eigenvalue to the sum of all eigenvalues.