just adding... after `x2.diff(v)` the `v` must be replaced by `a + c**2` again...
2013/11/2 Saullo Castro <[email protected]> > I believe we can make a variable transform and then apply the derivative > using the expression converted to a variable, like: > > x = a**2 + c + d**3 > x.diff((a + c**2)) > > changing variables: > > v = a + c**2 > a = v - c**2 > c = (v-a)**0.5 > > the new x will be: > > x2 = (v-c**2)**2 + (v-a)**0.5 + d**3 > > and the derivative could be computed as: > > x2.diff(v) > > is that reasonable? > > > 2013/11/2 F. B. <[email protected]> > > >> >> On Saturday, November 2, 2013 12:23:00 AM UTC+1, brombo wrote: >>> >>> Consider Lagrangian field theory where the derivatives are taken with >>> respect to the gradient of a field. In the case of quantum electrodynamics >>> with respect to the gradient of a spinor field. >>> >> >> Yes, that would be needed. I am wondering, is there a generic algorithm >> for functional derivatives, or is it more likely to be a complicated matter? >> >> -- >> You received this message because you are subscribed to a topic in the >> Google Groups "sympy" group. >> To unsubscribe from this topic, visit >> https://groups.google.com/d/topic/sympy/P8Q3G5bHe-U/unsubscribe. >> To unsubscribe from this group and all its topics, 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. >> For more options, visit https://groups.google.com/groups/opt_out. >> > > -- 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. For more options, visit https://groups.google.com/groups/opt_out.
