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 2007

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

Search the Archive

Some questions about vector

  • To: mathgroup at
  • Subject: [mg74543] Some questions about vector
  • From: "Qi Zhang" <qzhang81 at>
  • Date: Sun, 25 Mar 2007 01:26:48 -0500 (EST)


f[v] = Sum[(i*v[i]), {i, 1, N}]
D[f[v], v[i]]

the output is

\!\(1\/2\ N\ \((1 + N)\)\)

However what I expect is i

What should I do in order to get the the answer I expected?

Thanks a lot.

Qi Zhang

  • Prev by Date: Re: compile speed
  • Next by Date: No O Reilly Mathematica Cookbook
  • Previous by thread: Re: Integrate (a difficult integral)
  • Next by thread: Re: Some questions about vector