This happens because %phi is a constant, 1.681803...
It is as though you asked for 'diff(%pi,t).
This does not depend on t.
> -----Original Message-----
> From: maxima-bounces at math.utexas.edu [mailto:maxima-
> bounces at math.utexas.edu] On Behalf Of Wang Yuheng
> Sent: Wednesday, November 22, 2006 7:42 PM
> To: maxima at math.utexas.edu
> Subject: A problem aobut greek variable
>
> Code:
> (%i1)eq:'diff(%phi,t);
> (%o1)0
>
> Why? If I raplace '%phi' by a latin letter such as 'f', it displays:
> (%i2)eq:'diff(f,t);
> (%o2) df
> ----
> dt
> Why?
> _______________________________________________
> Maxima mailing list
> Maxima at math.utexas.edu
> http://www.math.utexas.edu/mailman/listinfo/maxima