Possible problem with dimensions in matrix products

*To*: mathgroup at smc.vnet.net*Subject*: [mg9211] Possible problem with dimensions in matrix products*From*: slater at itp.ucsb.edu (Paul Slater)*Date*: Tue, 21 Oct 1997 02:03:25 -0400*Sender*: owner-wri-mathgroup at wolfram.com

I have two 4-vectors (x and y) and a 4 x 4 matrix (Z). I want to compute x.Z.y, giving me a scalar. If I assign numerical values to the (three) parameters in x, y and Z, I do get a scalar. However, if I do not, then MATHEMATICA tells me that the product x.Z.y is a 3-vector (!!!!) The entries of the matrix and vectors are complex numbers. Paul Slater