Represents an arithmetic function, like math.max(arg1,arg2) -- a functor (math.max) and two arguments.
A Structure is thus used to store the data.
- - "arguments (from Structure.terms)" 0..* Term
returns true if the function/expression was already evaluated
Does a "normal" apply and then solve the expression and store the result,
so future calls of solve do not need to compute the value again
computes the value for this arithmetic function (as defined in the NumberTerm interface)
if (t == null) return false;
return "Error in '"+this+"' ("+ super.getErrorMsg() + ")";