       Symbolic Derivatives with respect to a vector

• To: mathgroup at smc.vnet.net
• Subject: [mg19929] Symbolic Derivatives with respect to a vector
• From: Tim Lahey <tjlahey at mud.cgl.uwaterloo.ca>
• Date: Tue, 21 Sep 1999 02:22:57 -0400
• Organization: Computer Graphics Lab - University of Waterloo
• Sender: owner-wri-mathgroup at wolfram.com

```Hi,

I am wondering if Mathematica can handle symbolic derivatives with
respect to a vector. I am
performing a Method of Ritz approximation and I have to get the
Euler-Lagrange equations.

As an example, here is part of an equation I have to take the
derivatives of:

a'*Aij*a + a'*Aij*b + b'*Aij*a

where a and b are vectors, ' indicates a transpose, and Aij is a matrix.
In order to get
the Euler-Lagrange equations I have to take the derivatives with respect
to a and b. I
can do this by hand but is it possible to do this symbolically ?

Thanks,

Tim Lahey

----
Tim Lahey
M.A.Sc Student - Systems Design Engineering
University of Waterloo, Waterloo, Ontario, Canada
http://www.cgl.uwaterloo.ca/~tjlahey/

```

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