[Maxima] How to assign a derivative of a function to a new function?

[Jaime Villate]

On Fri, 2008-05-09 at 12:01 +0200, Philippe Boeraeve wrote:
> am trying to assign a derivative to a new function, in order to know 
> the value of the derivative of the function at one point.

Besides the two methods that others have pointed out, there is a third
method:

(%i2) define(y(x), a*x^3+b*x^2+c*x+d)$

(%i3) define(dy(x), diff(y(x),x))$

Regards,
Jaime Villate