# Concerning the equation mode

I am listing a bunch of itens that are left-aligned (actually, I am using the \hspace command); then, for one of them, I need to do a definition by cases, so i'm using the equation mode and, inside it, the case mode. My problem is: when I do it like that this item comes centered, and I can't seem to find a way to put it left-align. Any suggestions?

EDIT: I'd like to have this implemented in a local-way; that is, generically equations would still be centered but in this particular case I'd like to be able to have them left-aligned...

MWE

\documentclass[11pt,a4paper]{book}

\usepackage[portuguese]{babel}

\usepackage[utf8]{inputenc}

\usepackage[T1]{fontenc}

\usepackage{amssymb}

\usepackage{amsmath}

\usepackage{amsthm}

\usepackage{indentfirst}

\begin{document}

\hspace{1.5cm} $x = something....$

\hspace{1.5cm} $y = something...$

\begin{equation*}
z =
\begin{cases}
1 & \text{if } x > 0 \\
-1 & \text{if } x \leq 0.

\end{cases}
\end{equation*}

\end{document}

• Do you really have that blank line before \end{cases}? – egreg May 18 '14 at 20:21
• I am not sure, but I don't think it's a problem! – essay May 18 '14 at 20:23
• Could you please change the title of your question to something more specifically reflecting its topic? – user4686 May 18 '14 at 22:01
• You don't need an equation environment to use cases. Just do the z equation like the others: \hspace{1.5cm} z = \begin{cases}, etc. However, I would recommend some version of the itemize environment (as in the answer by Peter Grill), rather than \hspace, to get the indentation. – Dan May 19 '14 at 2:59 • i was avoiding itemize because i don't want any numbering/ bullet point/ things like that - but i am sure there's a way to avoid this, i'll look into it. – essay May 19 '14 at 11:05 ## 3 Answers I would suggest you use a list environment, such as itemize with the enumitem package, along with an inner math environment such as aligned: ## Notes: • The showframe packagewas used just to show the page margins. It is not needed in your actual use case. • You can adjust the setting of the leftmargin as desired to get the text all the way to the left. ## Code: \documentclass{book} \usepackage{showframe} \usepackage{amsmath} \usepackage{indentfirst} \usepackage{enumitem} \begin{document} \begin{itemize}[leftmargin=2.0cm] \item[] x = something....$\item[]$ y = something...$\item[]$\begin{aligned}
z = \begin{cases}
1 & \text{if } x > 0 \\
-1 & \text{if } x \leq 0.
\end{cases}
\end{aligned}$\end{itemize} \end{document}  • this is actually rather elegant and helpful, thank you. – essay May 19 '14 at 11:06 \documentclass[11pt,a4paper]{book} \usepackage[portuguese]{babel} \usepackage[utf8]{inputenc} \usepackage[T1]{fontenc} \usepackage[fleqn]{amsmath} \usepackage{amssymb,amsthm} %% CODE FOR ENVIRONMENT ALLOWING SOME DISPLAYS TO BE FLUSHLEFT %% BUT THE DEFAULT WITHOUT THE ENVIRONMENT REMAINS TO CENTER THEM \makeatletter \@fleqnfalse \@mathmargin\@centering \newenvironment{flmath}[1][0pt] {\@fleqntrue \@mathmargin#1\relax} {} \makeatother \begin{document} \textbf{left margin = 1.5cm} \noindent\hspace{1.5cm}$ x = something....$\noindent\hspace{1.5cm}$ y = something...$\begin{flmath}[1.5cm] \begin{equation*} z = \begin{cases} 1 & \text{if } x > 0 \\ -1 & \text{if } x \leq 0. \end{cases} \end{equation*} \end{flmath} \textbf{left margin = parindent} \indent\smash{\rule[-2cm]{1pt}{2.2cm}}\kern-1pt$z$\begin{flmath}[\parindent] \begin{equation*} z = \begin{cases} 1 & \text{if } x > 0 \\ -1 & \text{if } x \leq 0. \end{cases} \end{equation*} \end{flmath} \textbf{Normal centered equations} \hrule \begin{equation*} z = \begin{cases} 1 & \text{if } x > 0 \\ -1 & \text{if } x \leq 0. \end{cases} \end{equation*} \hrule \end{document}  Here's another way, using stacks and \scalerel, the latter which scales the (width-constrained) brace to the size of what follows \documentclass[11pt,a4paper]{book} %\usepackage[portuguese]{babel} %\usepackage[utf8]{inputenc} %\usepackage[T1]{fontenc} %\usepackage{amssymb} %\usepackage{amsmath} %\usepackage{amsthm} %\usepackage{indentfirst} \usepackage{scalerel} \usepackage{tabstackengine} \def\ind{\par\noindent\hspace{1.5cm}} \setstacktabulargap{1em} \begin{document} \ind$ x = something....$\ind$ y = something...$\ind$z = \addstackgap{\scalerel[1.7ex]{\{}{%
\tabularCenterstack{rl}{%
$1$ & if $x > 0$ \\
$-1$ & if $x \protect\leq 0.$%
}}}\$
\end{document}