# splitting equation with matrices into multiple lines

I'm struggling to split an equation with matrix math into multiple lines. I've tried multline and aligned environments with no luck. It doesn't seem to handle having the matrices within this equation.

here's my code without any splitting attempts:

$$T'_{corr}(z)= \begin{bmatrix} n t_{0,c} + m t_{sel,c} & n t_{0,i} + m t_{sel,i} & n t_{0,j} + m t_{sel,j} & n t_{0,k} + m t_{sel,k} & n t_{0,u} + m t_{sel,u} & n t_{0,v} + m t_{sel,v}\\ \end{bmatrix} \begin{bmatrix} \delta\phi'_c(z) \\ \delta\phi'_i(z) \\ \delta \phi'_j(z) \\ \delta\phi'_k(z) \\ \delta\phi'_u(z) \\\delta\phi'_v(z) \\ \end{bmatrix}$$

• This code corresponds so a single-lined equation. Could you post a (complete) code of what you've tried? Commented Feb 10, 2022 at 16:00
• Welcome to TeX.SE. Is is ok to replace the row vector with the transpose of a column vector?
– Mico
Commented Feb 10, 2022 at 17:45

Instead of typesetting a 6-element row vector, I would typeset the transpose of the corresponding column vector.

You're of course free to choose a different symbol than ^{T} to denote transposition.

\documentclass{article}
\usepackage{mathtools} % for '\smashoperator' macro

\begin{document}
$$T'_{\mathrm{corr}}(z)= \begin{bmatrix} n t_{0,c} + m t_{\mathrm{sel},c} \\ n t_{0,i} + m t_{\mathrm{sel},i} \\ n t_{0,j} + m t_{\mathrm{sel},j} \\ n t_{0,k} + m t_{\mathrm{sel},k} \\ n t_{0,u} + m t_{\mathrm{sel},u} \\ n t_{0,v} + m t_{\mathrm{sel},v} \end{bmatrix}^{T}\! \begin{bmatrix} \delta\phi'_c(z) \\ \delta\phi'_i(z) \\ \delta\phi'_j(z) \\ \delta\phi'_k(z) \\ \delta\phi'_u(z) \\ \delta\phi'_v(z) \end{bmatrix} = \!\! \smashoperator[r]{\sum_{\kappa\in\{c,i,j,k,u,v\}}} (nt_{0,\kappa}+mt_{\mathrm{sel},\kappa})\,\delta\phi'_{\kappa}(z)$$
\end{document}


First matrix is far longer than \textwidth ... so ti may be solution to split it in three lines:

\documentclass{article}
\usepackage{mathtools}

\begin{document}
\begin{gather}
T'_{corr}(z)=
\left[\begin{multlined}