Re: [sympy] Bug with substituting derivatives

2015-05-19 Thread Jonathan Lindgren
of phi with respect to z? It seems like this substitution is saying that phi(z,t).diff(z) = phi(z,t) I'm new to sympy, so I apologize if this is a stupid question. Alex On 05/19/2015 12:16 PM, Jonathan Lindgren wrote: I recently updated from sympy 0.7.4 (I tihnk) to 0.7.6 and now I have

[sympy] Bug with substituting derivatives

2015-05-19 Thread Jonathan Lindgren
I recently updated from sympy 0.7.4 (I tihnk) to 0.7.6 and now I have some very strange behaviour with subs. The following code from sympy.abc import phi import sympy as sp z=sp.Symbol('z') t=sp.Symbol('t') sp.pprint((phi(z,t).diff(t,2)).subs(phi(z,t).diff(z),sp.Symbol('b')(z,t)).expand())