Thanks again on your timely reply. 1. I had indeed downloaded the zip file just as a precaution.
2. On playing around with the source code , I found out that, it is because of the unevaluated derivative , that leads to a wrong output. But in cases like the above mentioned, I guess there should be an option, by which we can directly integrate it , something like dsolve(d, f, hint = 'direct') . It maybe inconsequential in cases like above , but in cases like Derivative(x* f(x), x , x , x) , where it could give a solution by direct integration (without preprocessing) ,and preprocessing would give a NotImplementedError I think it would be helpful. This is my attempt at solving the problem, https://github.com/sympy/sympy/pull/1814 . On Fri, Feb 22, 2013 at 7:48 PM, Stefan Krastanov < [email protected]> wrote: > Hi, > > There are a few things that I find unclear, however I do reproduce > this behavior. > > First, there is no need to download any zip files (I guess you did it > as a precaution). Please just use git so we can use the commit hashes > and know about what revisions of the code we are talking. > > Then, be aware that there is no building/compiling in python. It is > interpreted language (there are some unimportant detail about .pyc > caches). If you have changed the code you are using the changed > version. > > Here is what I got: > > >>> f = f(x) > >>> d = Derivative(x * f , x) > >>> dsolve(d , f) > Cā > f(x) = āā > x > >>> dsolve(d , f , prep = False) > f(x) = Cā > > I am quite sure that this happened because `d` was constructed as an > unevaluated derivative. After > > d = d.doit() > > all works well. > > > I am not sure whether this should be considered a bug. After all sympy > permits you to construct many unevaluated objects > (Add(evaluate=False), Mul(evaluate=False), Integral, Derivative, Sum) > but does not promise to work well with them. > > -- > You received this message because you are subscribed to the Google Groups > "sympy" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/sympy?hl=en. > For more options, visit https://groups.google.com/groups/opt_out. > > > -- Regards, Manoj Kumar, Mech Undergrad. BPGC Blog <http://manojbits.wordpress.com> -- You received this message because you are subscribed to the Google Groups "sympy" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/sympy?hl=en. For more options, visit https://groups.google.com/groups/opt_out.
