Services & Resources / Wolfram Forums
MathGroup Archive
*Archive Index
*Ask about this page
*Print this page
*Give us feedback
*Sign up for the Wolfram Insider

MathGroup Archive 1998

[Date Index] [Thread Index] [Author Index]

Search the Archive

Problem with sums differentiation

  • To: mathgroup at
  • Subject: [mg13143] Problem with sums differentiation
  • From: Dmitri Tcherniak <famdt at>
  • Date: Mon, 13 Jul 1998 07:41:56 -0400
  • Sender: owner-wri-mathgroup at

I have problems with infinite sums integration, differentiations,
multiplications when the imax is infinity or a symbol. For example

a[x_,t_]=Sum[uj[t]*Cos[j Pi x],{j,1,Infinity}]; Dt[a[x,t],x]

gives me
Out: Dt[Sum[uj[t] Cos[j Pi x], {j, 1, Infinity}], x]

but not something like Sum[-uj[t]*j*Pi*Sin[j Pi x],{j,1,Infinity}]

Is there a way to move the integration (differentiation) sigh under the
sum sigh and force Mathematica to evaluate the terms?

Thank you
Dmitri Tcherniak

  • Prev by Date: Electrical Engineering package
  • Next by Date: Re: Re: Re: declaring integers
  • Previous by thread: Electrical Engineering package
  • Next by thread: Re: Problem with sums differentiation