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? -- 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.
