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/