Thanks, Aaron. That works, though I had hoped for something prettier than:
Subs(Derivative(f(_x), _x), (_x,), (x0,)) It would be really great if sympy knew how to print this kind of thing nicely (say, in an IPython notebook). -David On Wed, Jan 16, 2013 at 9:25 PM, Aaron Meurer <[email protected]> wrote: > Try Subs(diff(f, x), x, x0). > > Note that mathematically, this should be the same as diff(f, > x).subs(x, x0), because x is a bound (not free) variable in this > expression, it doesn't matter if a different one is used, or if an > expression is used that doesn't use it at all. Note that if you use a > non-variable instead of x0, it will automatically give you the Subs > form (in particular, if you use a number, like diff(f, x).subs(x, > 10)). It will also give you the Subs form if you later substitute x0 > for a number (in terms of x0, but it doesn't matter because x0 serves > as a dummy variable in this case). > > Aaron Meurer > > On Wed, Jan 16, 2013 at 5:06 AM, David Ketcheson <[email protected]> wrote: > > Is there any way in sympy to express the derivative of an abstract > function > > evaluated at a point? I can do > > > > import sympy > > x,x0 = sympy.var(('x','x0')) > > f=sympy.Function('f') (x) > > sympy.diff(f) > > > > to get the derivative w.r.t. x evaluated at x. If I do > > > > sympy.diff(f).subs(x,x0) > > > > then I get the derivative w.r.t. x0 evaluated at x0. Can I get the > > derivative w.r.t. x evaluated at x0? > > > > -- > > You received this message because you are subscribed to the Google Groups > > "sympy" group. > > To view this discussion on the web visit > > https://groups.google.com/d/msg/sympy/-/cQScvWEPp9MJ. > > To post to this group, send email to [email protected]. > > To unsubscribe from this group, send email to > > [email protected]. > > For more options, visit this group at > > http://groups.google.com/group/sympy?hl=en. > > -- > You received this message because you are subscribed to the Google Groups > "sympy" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]. > For more options, visit this group at > http://groups.google.com/group/sympy?hl=en. > > -- You received this message because you are subscribed to the Google Groups "sympy" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/sympy?hl=en.
