code: private static double scoreAbsError(Integer pre, Integer image,int minPre,int maxPre) {
  		// Use the absolute error score, |x - f^k(x)|
  		double error;
  		if(image == null) {
  			error = Double.POSITIVE_INFINITY;
  		} else {
  			error = Math.abs(pre - image);
  		}
  
  		//TODO favor lower degree-in
  
  		// Add fractional portion relative to sequence position, for uniqueness
  		if(error > 0)
  			error += (double)(pre-minPre)/(1+maxPre-minPre);
  
  		return error;
  	}
docs: Calculate the score for a residue, specifically the Absolute Error
  score(x) = |x-f^k(x)|
  
  Also includes a small bias based on residue number, for uniqueness..
  @param pre x
  @param image f^k(x)
  @param minPre lowest possible residue number
  @param maxPre highest possible residue number
  @return