> Uwe Brauer <oub@mat.ucm.es> writes:


> I'm not very familiar with calc, but am wondering if the issue is the
> 'nan'. In many languages, a nan is a 'polluting' variable i.e. once you
> have a nan as a form anywhere in your calculation, the result will
> always be a nan. Many languages actually have a special function to test
> for a nan because it isn't actually a 'value'. Don't know if this is the
> case with calc. 

Yeah, when I googled, I found complains about nan using in calc but I
did not really found an working alternative.

> Perhaps an alternative strategy might help. Could you address what is
> generating the nan and change that so that it generates something else,
> possibly even a blank string and avoid the nan altogether? 

I tried nil and other expressions but non really worked, so maybe a calc
guru could clarify?

Regards