Some questions about vector
- To: mathgroup at smc.vnet.net
- Subject: [mg74543] Some questions about vector
- From: "Qi Zhang" <qzhang81 at gmail.com>
- Date: Sun, 25 Mar 2007 01:26:48 -0500 (EST)
input:
Clear[f];
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.
--
Best,
Qi Zhang