try numberp "number predicate"
numberp(diff(x,x)) --> true
numberp(diff(x^2,x)) --> false
Good luck.
RJF
> -----Original Message-----
> From: maxima-admin at math.utexas.edu
> [mailto:maxima-admin at math.utexas.edu] On Behalf Of Wascar Bocangel
> Sent: Sunday, August 13, 2006 10:10 AM
> To: maxima at math.utexas.edu
> Subject: Re: Number or expression
>
> Hi, I'm a new user to Maxima and I would like to know if
> there's a function which can tell me if an output is a number
> or an expression. For example, if I use the command
> diff(exp,variable,2); then, I can get either a number, or a
> polynomial expression. I want to know if there's a function
> that can return a true or false in this situation.
>
>
>
> Thanks for your time,
>
>
>
> --
> Wascar Bocangel
>