How to left align the equation

Question

I am using below equation in my document. By default, it is getting aligned at the center. I want to left-align the equation -- only this equation, not all equations in the document. Can anybody tell me how it can be done?

\begin{equation}
d_j =
  \begin{cases}
    newval_i,  & \quad i = j\\
    randval_k, & \quad k = j\\
    bestval_j, & \quad \text{otherwise}
  \end{cases}
\end{equation}

unrelated to alignment but that should be \mathit{newval}_i and similarly the other names, never use the default math italic for multi-letter words. — David Carlisle, Apr 29 '17 at 16:19
@Atinesh - The fact that you only wish to left-align a single equation is very important, and unfortunately it's something that wasn't mentioned in your posting. It's not too late, though, to edit your posting and to clarify what it is you're trying to achieve. Go ahead. — Mico, Apr 29 '17 at 16:47
@Bobyandbob I have already gone through that post, It didn't solve my problem. — Atinesh, Apr 29 '17 at 17:00
I've edited and "reopened" this posting. In the edit, I provided some (apparently much needed) emphasis on the fact that the OP wishes to left-align only one particular equation, not all equations in the document. Hence, the suggestion to use set the fleqn option isn't applicable here. — Mico, Apr 29 '17 at 17:28

Bernard · Accepted Answer · 2017-04-29T19:19:35.997

You can do that nesting your equations in a fleqn environment (from nccmath). This environment accepts an optional argument for the distance from the left margin ( 0 pt by default):

\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage[showframe]{geometry}
\usepackage{mathtools, nccmath}

\begin{document}

\begin{equation}
d_j =
  \begin{cases}
    \text{newval}_i, & \quad i = j\\
    \text{randval}_k, & \quad k = j\\
    \text{bestval}_j, & \quad \text{otherwise}
  \end{cases}
\end{equation}

\begin{fleqn}
\noindent\texttt{With fleqn: }
\begin{equation}
d_j =
  \begin{cases}
    \text{newval}_i, & \quad i = j\\
    \text{randval}_k, & \quad k = j\\
    \text{bestval}_j, & \quad \text{otherwise}
  \end{cases}
\end{equation}
\end{fleqn}

\begin{fleqn}[3em]
\noindent\texttt{With fleqn and optional argument [3em]: }
\begin{equation}
d_j =
  \begin{cases}
    \text{newval}_i, & \quad i = j\\
    \text{randval}_k, & \quad k = j\\
    \text{bestval}_j, & \quad \text{otherwise}
  \end{cases}
\end{equation}
\end{fleqn}

    \end{document}

Thanks, @Mico. The package has many useful little things – the main point for me being medium-sized maths, intermediate between display style and text style for fractions, integrals, matrices and so on. — Bernard, Apr 29 '17 at 20:16

How to left align the equation

1 Answers1