Provides an interface for automatically evaluating formulas based on user-defined operators and functions. The VisAD formula package is accessed through the FormulaManager class. The constructor for the FormulaManager class takes user-defined operators, operator precedences, and functions as arguments. Then, variables can be bound to pre-existing ThingReferences with the FormulaManager.createVar() method, bound to formulas with the FormulaManager.assignFormula() method, or set directly with the FormulaManager.setThing() method. The FormulaManager.getThing() method returns the current value of a variable, and the FormulaManager.remove() method deletes a variable. Variables update automatically when the variables upon which they depend change. For an example of usage, see the visad.ss package.