graphdb/src/main/java/com/orientechnologies/orient/graph/sql/functions/OSQLFunctionHeuristicPathFinderAbstract.java
protected double getSimpleHeuristicCost(double x, double g, double dFactor) {
        double dx = Math.abs(x - g);
        return dFactor * (dx);
    }
protected double getSimpleHeuristicCost(double x, double g, double dFactor) {
        double dx = Math.abs(x - g);
        return dFactor * (dx);
    }
obtains from http://theory.stanford.edu/~amitp/GameProgramming/Heuristics.html