Re: Some questions about vector

*To*: mathgroup at smc.vnet.net*Subject*: [mg74594] Re: Some questions about vector*From*: "Sem" <sarner2006-sem at yahoo.it>*Date*: Tue, 27 Mar 2007 04:06:51 -0500 (EST)*References*: <eu54qn$l30$1@smc.vnet.net>

Do you mean a linear combination of vectors, like this v = a1*v1 + a2*v2 + ... + an*vn where v, v1,...,vn are vectors of a vector space (e.g. R^n ) and a1,a2,...,an are elements of a field ? I don't know if exists any package that treats general vector analysis but it sounds interesting to working around it. Bye, S. "Qi Zhang" <qzhang81 at gmail.com> ha scritto nel messaggio news:eu54qn$l30$1 at smc.vnet.net... > 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 >