       Re: A question about derivatives of quadratic products

• To: mathgroup at smc.vnet.net
• Subject: [mg49091] Re: A question about derivatives of quadratic products
• From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
• Date: Thu, 1 Jul 2004 05:25:35 -0400 (EDT)
• Organization: Universitaet Leipzig
• References: <cbu35t\$5m1\$1@smc.vnet.net>
• Reply-to: kuska at informatik.uni-leipzig.de
• Sender: owner-wri-mathgroup at wolfram.com

```Hi,

nobody can help you if you are not able to read the
manual. A sum is written as Sum[term,{i,1,n}] an
square root as Sqrt[] and only you know what "&#945;"
means.

Regards
Jens

afh wrote:
>
> Hello,
> I am a new user of mathematica. I met a question about derivatives as
> following:
> D = Norm[w, 2]^2/2+sum(&#945;i(yi(w.x+b+sqrt(w.M.w))-1)) (which i=1 to
> n)
> w and x are two-dimension vectors, yi is a number either -1 or 1, b is
> a number, M is a 2*2 matrix, &#945;i is a lagrange coefficient.
> I want to get the value of w when D's derivative on w is equal to
> zero.
> But many errors happen, and it seems mathematica does not know what it
> should do next. Can somebody help me? Many thanks for your kind help.

```

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