Sign of a symbolic algebraic expression
Is there any algorithm that can find the sign of an arbitrary symbolic algebraic expression given in a "Tree - Form"? I know that a general algorithm doesn't exist because the zero recognizion problem is undecidable for an arbitrary expression, but how should I approach the problem of finding the sign of an expression? (how is this done in computer algebra?) For example: sign(sqrt(2)-1) = ? Evaluate the function value You need function evaluator engine for that (it is not that hard to code) there is no way to evaluate sign only if you want to support +,- operations !!! All my function