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Re: symbolic and indefinite differentiation


Hi,

expr = Sum[a[k]*x^k, {k, 1, p}];
D[expr, x] /. HoldPattern[Sum[a_, b__]] :> Sum[Evaluate[a], b]

???

Regards
  Jens

Philippe Huber wrote:
> 
> Hello,
> 
> I have a dummy question: I would like to know if it is possible (and how) to
> differentiate a symbolic sum like
> 
> f(x1,...,xn)=Sum[x^2[[k]],{k,1,p}]
> 
> with respect to xi. I should obtain 2xi.
> 
> Thank you for your help
> 
> Philippe


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