Although using the rules of derivative is good idea, I'm not really sure that SymPy currently has the class for 'd' operator.
And, regarding to your second reply, df(t-1)/dt will be good for AppliedUndef classes. Written in SymPy code, it will be Subs(Derivative(f(t),t), (t,), (x+1)). Then, how about letting f(x).diff(x+1) result this? Also, let's say if the expression is not AppliedUndef but other class, e.g. Add. For example, dx/d(x+1). In this case, substituting x+1 with t can evaluate this to 1, so I think x.diff(x+1) can return 1 as well. Let me summarize: - Differentiating AppliedUndef with x+1 results Subs(Derivative(f(t),t), (t,), (x+1)). - Differentiating other classes, such as Add or Mul, results the evaluated value, if possible. How do you think of it? 2020년 1월 5일 일요일 오전 2시 51분 8초 UTC+9, Vishesh Mangla 님의 말: > > Wrong if you want to use substitution then it should be df(t-1)/dt. > > > > Sent from Mail <https://go.microsoft.com/fwlink/?LinkId=550986> for > Windows 10 > > > > *From: *David Bailey <javascript:> > *Sent: *04 January 2020 22:52 > *To: *[email protected] <javascript:> > *Subject: *Re: [sympy] Suggestion on Derivative and Expr._diff_wrt > > > > On 04/01/2020 13:08, mcpl snu wrote: > > It's same as df(t)/dt, where t=x+1. > > > > Thanks, and I suppose that also generalises to expressions such as > df(x)/d(sin(x))? > > df(t)/dt where t=sin(x) > > Given how easy it is to mistype input to sympy, I don't think such an > extension is such a good idea. > > David > > -- > 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] <javascript:>. > To view this discussion on the web visit > https://groups.google.com/d/msgid/sympy/d517dc5a-3939-48dd-9d53-db458822ac11%40dbailey.co.uk > > <https://groups.google.com/d/msgid/sympy/d517dc5a-3939-48dd-9d53-db458822ac11%40dbailey.co.uk?utm_medium=email&utm_source=footer> > . > > > -- 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 view this discussion on the web visit https://groups.google.com/d/msgid/sympy/ab7b7b8b-42e5-4435-bc28-5396aa872c9f%40googlegroups.com.
