# How to break equations in between multiple cases environment

I was wondering if anyone could assist me with the the following problem: The equation below has 4 different blocks and is too long to fit on one line. Ideally I would like to break it into two and put one half below the first half. Any ideas how to do this? I've tried \\ and aligned but don't seem to be getting the right results.

\documentclass{article}
\usepackage{amsmath}

\begin{document}

$$\label{int_num_test} x_{i} = \eta1 \times \begin{cases} (1 + \eta8(age - 5.4)) & age \le 10\\ (1 + \eta9(age - 5.4)) & age > 10\\ \end{cases} \times \begin{cases} 1 & \text{Case 1}\\ 1 + \eta12 & \text{Case 2}\\ 1 + \eta13 & \text{Case 3}\\ 1 + \eta14 & \text{Case 4}\\ \end{cases} \times \begin{cases} 1 & Case 5\\ 1 + \eta10 & Case 6\\ \end{cases} \times (1 + \eta11(v - 5.08))$$

\end{document}


Hmm a couple of alternatives here, neither particularly readable, I'd be tempted to define variables for the case terms and then just show it as a\times b\times c \times d but

\documentclass{article}
\usepackage{amsmath}

\begin{document}
\newcommand\age{\mathrm{age}}

$$\label{int_num_test} \begin{split} x_{i} = \eta1 \times \begin{cases} (1 + \eta8(\age - 5.4)) & \age \le 10\\ (1 + \eta9(\age - 5.4)) & \age > 10\\ \end{cases} \times \begin{cases} 1 & \text{Case 1}\\ 1 + \eta12 & \text{Case 2}\\ 1 + \eta13 & \text{Case 3}\\ 1 + \eta14 & \text{Case 4}\\ \end{cases} \\ \times \begin{cases} 1 & \text{Case 5}\\ 1 + \eta10 & \text{Case 6}\\ \end{cases} \times (1 + \eta11(v - 5.08)) \end{split}$$
or
$$\label{int_num_testq} \begin{gathered} x_{i} = \eta1 \times \begin{cases} (1 + \eta8(\age - 5.4)) & \age \le 10\\ (1 + \eta9(\age - 5.4)) & \age > 10\\ \end{cases}\\ \times \begin{cases} 1 & \text{Case 1}\\ 1 + \eta12 & \text{Case 2}\\ 1 + \eta13 & \text{Case 3}\\ 1 + \eta14 & \text{Case 4}\\ \end{cases} \\ \qquad \times \begin{cases} 1 & \text{Case 5}\\ 1 + \eta10 & \text{Case 6}\\ \end{cases}\\ \qquad\qquad \times (1 + \eta11(v - 5.08)) \end{gathered}$$

\end{document}

• Thanks for the attempt, I'll consider re-defining variables. Do you mind explaining what \newcommand\age{\mathrm{age}} does? – John_dydx Oct 17 '16 at 19:58
• @John it just defines \age to be \mathrm{age} to save writing \mathrm{age} every time, never use math italic for multi-letter words the font is designed with wide sidebearings to make adjacent letters not look like a word but as the product a*g*e. – David Carlisle Oct 17 '16 at 20:02