On Sun, Jun 19, 2011 at 7:34 PM, Renato Coutinho <[email protected]>wrote:
> On Sun, Jun 19, 2011 at 9:30 PM, Chris Smith <[email protected]> wrote: > > > > > > On Sun, Jun 19, 2011 at 7:05 PM, Renato Coutinho < > [email protected]> > > wrote: > >> > >> Hello, > >> > >> On Sun, Jun 19, 2011 at 3:51 PM, Mani Chandra <[email protected]> wrote: > >> > Hi, > >> > Is it possible to tell simplify that the partial derivatives with > >> > respect to > >> > two different variable commute so that it can simplify further? For > ex: > >> > d^2 f/dxdy + d^2 f/dydx > >> > The above expression is left as it is by simplify(), but it would be > >> > nice if > >> > there were some way to tell it about the commutation so that it can > >> > simplify > >> > further. > >> > >> This is fixed in current development version, so that > >> > >> >>> f(x, y).diff(x, y) - f(x, y).diff(y, x) > >> 0 > >> > >> If you don't want this to happen, you have to use unevaluated > >> derivatives (diff() always evaluates them): > >> > >> >>> Derivative(f(x, y), x, y) - Derivative(f(x, y), y, x) > >> D(f(x, y), x, y) - D(f(x, y), y, x) > >> > > > > Notice that he used "+" not "-" -- does he want `2*D(f(x,y), x, y)` to be > > returned? > > Yes, I think that's what he meant, and it works too, returning > 2*D(f(x, y), x, y). > > Then, Mani, it would be good if you showed the actual input (not ASCII math) for what you entered and what you got. Just copy and paste like Renato did in his examples. -- 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.
