Continuing the previous message... I would find it extremely useful if it was possible to get a numeric representing the ex's contents, _if_ that is possible, of course. Specifically, it would a be a function like this: class ex { .... numeric to_numeric() const; .... } Or any other significant name. Of course, there are times when a numeric cannot represent an ex. In these cases, the most appropriate solution seems to throw an exception, but other ways of allerting the user are possible. Another function, returning a bool saying wheter the ex can be converted into a numeric would also be nice. Is the above possible? -- The church is near but the road is icy; the bar is far away but I will walk carefully. -- Russian Proverb Eduardo M Kalinowski (ekalin@iname.com) http://move.to/hpkb http://cami-ufpr.hpg.com.br - To UNSUBSCRIBE, email to ginac-list@ginac.de with a subject of "unsubscribe".