# print the rows of a matrix in two different sections in order to prevent the elements from mixing together

As you see in the following picture I have a 4x4 matrix and the elements are so lengthy that they will not fit in a single line of an A4 paper.
In fact this equation is printed in a book that I'm translating. I'm not familiar with LateX and I'm just typing mathematical expression with LaTex in Mathtype. So I can only use amsmath package and math-mode codes

The question is how can I create the exact shape of equation in my LaTex code?
what I have done so far, is the following code:

\begin{bmatrix}
. & . & . & .\\
. & . & . & .\\
. & . & . & .\\
. & . & . & .
\end{bmatrix}


I know how to write each element of the matrix. In fact I know what to write instead of dots
I know for seperating elements of matrix in a single row, & should be used and to go to the next row, we should use \\
Also I'm familiar with \cdots, ldots and etc.
But I don't know how to rearrange the elements exactly like the picture and prevent them from mixing up together?

Edit:

\begin{align}
T_4 &= \langle \underline{k}\,.\,\underline{k}^{*^T} \rangle=
\left\langle
\begin{bmatrix}
\left|k_1\right|^2 & k_1k_2^* & k_1k_3^* & k_1k_4^*\\
k_2k_1^* & \left|k_2\right|^2 & k_2k_3^* & k_2k_4^*\\
k_3k_1^* & k_3k_2^* & \left|k_3\right|^2 & k_3k_4^*\\
k_4k_1^* & k_4k_2^* & k_4k_3^* & \left|k_4\right|^2
\end{bmatrix}
\right\rangle
\\
&=\frac{1}{2}
\begin{split}
\left[\begin{matrix}
\langle|S_{XX}+S_{YY}|^2\rangle &
\langle(S_{XX}+S_{YY})(S_{XX}-S_{YY})^*\rangle &\\
\langle(S_{XX}-S_{YY})(S_{XX}+S_{YY})^*\rangle &
\langle|S_{XX}-S_{YY}|^2\rangle & \cdots\cdots\\
\langle(S_{XY}+S_{YX})(S_{XX}+S_{YY})^*\rangle&
\langle(S_{XY}+S_{YX})(S_{XX}-S_{YY})^*\rangle & \cdots\cdots\\
\langle j(S_{XY}-S_{YX})(S_{XX}+S_{YY})^*\rangle &
\langle j(S_{XY}-S_{YX})(S_{XX}-S_{YY})^*\rangle &
\end{matrix}\right.\\
\left.\begin{matrix}
& \langle(S_{XX}+S_{YY})(S_{XY}+S_{YX})^*\rangle
& \langle -j(S_{XX}+S_{YY})(S_{XY}-S_{YX})^*\rangle\\
\cdots\cdots& \langle(S_{XX}-S_{YY})(S_{XY}+S_{YX})^*\rangle
& \langle -j(S_{XX}-S_{YY})(S_{XY}-S_{YX})^*\rangle\\
\cdots\cdots& \langle|S_{XY}+S_{YX}|^2\rangle
& \langle-j(S_{XY}+S_{YX})(S_{XY}-S_{YX})^*\rangle\\
& \langle j(S_{XY}-S_{YX})(S_{XY}+S_{YX})^*\rangle
& \langle|S_{XY}-S_{YX}|^2\rangle
\end{matrix}\right]
\end{split}
\end{align}


It is displayed like this math.stackexchange.com

• A minimal (non)working code would be nice to save us the tedium of typing the whole formulae. Could you post one so we can play with it? – Bernard Aug 9 '15 at 12:34
• It is a symmetric matrix. You don't need to type out every element. As you can see it takes quite some attention to see that it is a symmetric matrix which can be pretty obvious if you typeset it so. And what is the LR bracket operation, inner product? – percusse Aug 9 '15 at 13:41
• @percusse LR bracket is for ensemble averaging – Sepideh Abadpour Aug 9 '15 at 13:51
• @Bernard I'll start now to try out LaRiFaRi's answer, then I will post the code here if I need more help and save you the tedium of typing the whole question – Sepideh Abadpour Aug 9 '15 at 13:54
• @percusse: it isn't really symmetric, as I can see it. – Bernard Aug 9 '15 at 14:04

% arara: pdflatex
$% or if you want it numberd. \begin{split} \left[\begin{matrix} . & . &\\ . & . & \cdots\cdots\\ . & . & \cdots\cdots\\ . & . & \end{matrix}\right.\\ \left.\begin{matrix} & . & .\\ \cdots\cdots& . & .\\ \cdots\cdots& . & .\\ & . & . \end{matrix} \right] \end{split}$