[Ifeffit] formula checking

[Bruce Ravel]

> Bruce, would it help if a flag was set indicating 'syntax error'
> in addition to printing the warning message?

Yes, very much so.

> That way you could
> wrap each of the definitions with a perl function that did the
> ifeffit command and check for syntax errors, doing something
> sensible (popping up a warning dialog box, for example) on a
> syntax error.

Exactly.  That would be really helpful and a great service to the user.

> A flag meaning 'math error' (as on divide-by-zero or sqrt(-1))
> might be useful too, I suppose....

Yes indeed.

B