Writing a equation with many regions

Question

How to write a equation like the following which contain many regions? GHASH

Suggested cases is a good choice. You can also use array, if for some reason you don't want to use amsmath. But I can see some additional traps. In particular, what are len and ||? Their behaviour should depend on their function. — Przemysław Scherwentke, Dec 11 '13 at 16:09

score 4 · Accepted Answer · edited Mar 20 '17 at 13:35

4

Use cases environment

\documentclass{article}
\usepackage{amsmath}

\begin{document}\begin{equation}
f(n) = \begin{cases} n/2 &\mbox{if } n \equiv 0 \\
(3n +1)/2 & \mbox{if } n \equiv 1 \\
(3n +1)/2 & \mbox{if } n \equiv 1 
\end{cases}
\end{equation}
\end{document}

enter image description here

edited Mar 20 '17 at 13:35

David Carlisle

757,742

answered Dec 11 '13 at 15:47

Red

10,181

1

Better \text{…} than \mbox{…}. And if you load mathtools insteado of amsmath, you can use cases* environment, which sets the second column to text mode. – Manuel Dec 11 '13 at 16:34

score 3 · Answer 2 · edited Apr 13 '17 at 12:34

3

Here is MWE that can help you to begin:

enter image description here

\documentclass{article}
\usepackage{amsmath,amssymb}
\begin{document}
\[  X_i=
    \begin{cases}
    0                           & \text{ for } i=0\\
    (X_{i-1}\oplus A_i)\cdot H  & \text{ for } i=1,\dotsc,m-1
    \end{cases}
\]
\end{document}

Writing a equation with many regions

2 Answers2