private static Dimension valueOf(int id) {
            for (Dimension dim : values()) {
                if (id == dim.id) {
                    return dim;
                }
            }
            return null;
        }
This function decompose two-dimensonal zcurve values into x and y values.

@author baldersheim
searchlib/src/main/java/com/yahoo/searchlib/expression/ZCurveFunctionNode.java