function [ fh ] = screePlot( eigvals )
% 
% Plots a scree plot of the variances of the principle components.
% Taken from page 38 of 
%
% Exploratory Data Analysis with MATLAB 
% by Martinez and Martinez.
%
% Written by:
% -- 
% John L. Weatherwax                2005-08-14
% 
% email: wax@alum.mit.edu
% 
% Please send comments and especially bug reports to the
% above email address.
% 
%-----

% make sure we have a row vector (with postive values): 
eigvals = abs(eigvals(:).'); 

% Sort eigenvalues in decreasing order:
[ eigvals ] = sort( eigvals ); eigvals = fliplr( eigvals ); 

fh=figure; 
%subplot(1,2,1); 
plot( eigvals, '-ok' ); 
%plot( log(eigvals), '-ok' ); 

axis tight;  grid on; 
xlabel( 'Eigenvalue Index - k' ); ylabel( 'Eigenvalue Magnitude' ); 
title( 'scree plot' ); 

%subplot(1,2,2); 
%plot( log(eigvals), '-ok' ); axis tight;