# Symbolic matrix calculation [closed]

I have question about a matrix calculation like $\mathbf{b}^{t}\,\Sigma\,\mathbf{b}$, where $\Sigma$ is a 7 by 7 matrix, and $\mathbf{b}$ is vector of 7 elements, and each element in the vector $\mathbf{b}$ or $\Sigma$ is a symbolic formula,

For example, the (i, j)-th element of $\Sigma$ could have the form $\Sigma_{i,j}=ab+c+u+m$.

How can I do this calculation in Mathematica?

-

## closed as off-topic by MarcoB, Yves Klett, Sjoerd C. de Vries, Mr.Wizard♦Jun 25 '15 at 6:31

This question appears to be off-topic. The users who voted to close gave this specific reason:

• "This question arises due to a simple mistake such as a trivial syntax error, incorrect capitalization, spelling mistake, or other typographical error and is unlikely to help any future visitors, or else it is easily found in the documentation." – MarcoB, Sjoerd C. de Vries, Mr.Wizard
If this question can be reworded to fit the rules in the help center, please edit the question.

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.

-