After much googling and ogling various web sites, I believe I have
stumbled on a bug in Maxima having to do with evaluating functions that
are derivatives of other functions for given values of the independent
variable.
Consider:
(%i1) f(x):=sin(x);
(%o1) f(x):=sin(x)
(%i2) f(%pi);
(%o2) 0
(%i3) f(4*%pi);
(%o3) 0
(%i4) g(x):='' diff(f(x),x);
(%o4) g(x):=diff(f(x),x)
(%i5) g(x);
(%o5) cos(x)
(%i6) g(%pi);
(%o6) 0
(%i7) g(4*%pi);
Non-variable 2nd argument to diff:
4*%pi
#0: g(x=4*%pi)
-- an error. To debug this try debugmode(true);
I am not sure why g(%pi) evaluates fine, but g(4*%pi) does not. I know
my syntax for specifying 4 pi is correct, since the same works for
evaluating f(x) at 4 pi.
Any help in determining why this does not work, and how to get it work,
would be much appreciated.
--Moby