Le jeudi 22 octobre 2009 à 14:42 -0700, Ondrej Certik a écrit : > On Thu, Oct 22, 2009 at 2:34 PM, andy2O <and...@hotmail.com> wrote: > > > > > > Hi all, > > > > as_coeff_exponent(...) seems to ignore derivatives, as shown below > > > > Is this behaviour intended? If so I can report it as an issue - but > > last time recorded an issue it turned out I just misunderstood atoms > > (), so I thought I'd check first here! :) > > Sure. :) > > > > > Thanks, > > andy > > > >>>> ================================ RESTART ================================ > >>>> from sympy import * > >>>> var('x') > > x > >>>> f=Function('f') > >>>> d=diff(f(x),x) > >>>> d > > D(f(x), x) > >>>> d.as_coeff_exponent(f(x)) > > (1, 1) > > What do you suggest to be a correct answer? I never used > as_coeff_exponent inside a derivative. > > Ondrej
The correct answer is clearly (D(f(x), x), 0), by analogy with cos(x).as_coeff_exponent(sin(x)) == (cos(x), 0). So, yes, Andy, you've uncovered a real issue. I think that the fundamental problem here is that there is no object representing the derivative of a function (the current Derivative is an operation applying to expressions, not functions). Ronan --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "sympy" group. To post to this group, send email to sympy@googlegroups.com To unsubscribe from this group, send email to sympy+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sympy?hl=en -~----------~----~----~----~------~----~------~--~---