# symbol matrix calulation

I have question about matrix calculation. like $\mathbf{b}^{t}\Sigma \mathbf{b}$, where $\Sigma$ is 7 by 7 matrix, and $\mathbf{b}$ is vector of 7.

and each element in the vector b or $\Sigma$ is symbol formula,

for example the (i,j) th element of $\Sigma$, $\Sigma_{i,j}=ab+c+u+m$，etc， is there anyway to get the results from Mathematica?

-

You may need to use the "list" data structure in mathematica. Say, $\Sigma$ is a two by two matrix. In Mathematica, you just input

Sigma = {{x+y, m+n}, {x+y-w, m-n.l}}


Similarly

b={u,v}


Then, $b\Sigma b^T$ is just

b.Sigma.Transpose[b,{1}]


Hope it works for you.

-