// add SubtractFunction
generalFunctions.addAll((new SubtractFunctionCluster()).getSupportedFunctions());
// add MultiplyFunction
generalFunctions.addAll((new MultiplyFunctionCluster()).getSupportedFunctions());
// add DivideFunction
generalFunctions.addAll((new DivideFunctionCluster()).getSupportedFunctions());
// add ModFunction
generalFunctions.addAll((new ModFunctionCluster()).getSupportedFunctions());
// add AbsFunction
generalFunctions.addAll((new AbsFunctionCluster()).getSupportedFunctions());
// add RoundFunction