code: public void process() {
  
  		computeCovarince();
  
  		float eigenvalue = smallestEigenvalue();
  		// eigenvalue is the variance, convert to standard deviation
  		double stdev = Math.sqrt(eigenvalue);
  //		System.out.println("stdev "+stdev+"  total "+norm.size()+"  mean "+meanX+"  "+meanY);
  
  		// approximate the spread in by doing it along the x-axis.
  		// Really should be along the smallest singular axis
  		double angle0 = Math.atan2(1.0,sigmas*(meanX-stdev));
  		double angle1 = Math.atan2(1.0,sigmas*(meanX+stdev));
  
  		spread = Math.abs(angle1-angle0);
  	}
docs: Computes the worst case spread for how features are laid out