# Could I be able to left-align the following equations? (Please note that one of which is mult-lined)

    \documentclass[11pt,a4paper]{article}
\usepackage{blindtext}
\usepackage{mathtools}
\DeclareMathOperator{\sgn}{sgn}
\begin{document}
\begin{flalign*}
&D=
\sum_{\epsilon(1,2,3)}\epsilon(1,2,3)a_{11}a_{22}a_{33}.&\\
&\end{flalign*}
\begin{multline*}
D=
\epsilon(1,2,3)a_{11}a_{22}a_{33}+\epsilon(1,3,2)a_{11}a_{23}a_{32}+
\epsilon(2,1,3)a_{12}a_{21}a_{33}+\\
\epsilon(2,3,1)a_{12}a_{23}a_{31}+\epsilon(3,1,2)a_{11}a_{21}a_{31}+
\epsilon(3,2,1)a_{13}a_{22}a_{31}.
\end{multline*}
\end{document}

-
Do you mean line up the two "D =" ? – Thruston Sep 4 '14 at 9:11
Yes, that was what I looked for. – Nisal Kevin Kotinkaduwa Sep 4 '14 at 9:31

mathtools provides a multlined environment, which is to multline as aligned is to align, so you can use this within the flalign. Note the negative space \!.

\documentclass[11pt,a4paper]{article}
\usepackage{mathtools}
\usepackage{showframe} % to indicate border of text area
\begin{document}
\begin{flalign*}
&D=
\sum_{\epsilon(1,2,3)}\epsilon(1,2,3)a_{11}a_{22}a_{33}.&\\
&\!\begin{multlined}
D=
\epsilon(1,2,3)a_{11}a_{22}a_{33}+\epsilon(1,3,2)a_{11}a_{23}a_{32}+
\epsilon(2,1,3)a_{12}a_{21}a_{33}+\\
\epsilon(2,3,1)a_{12}a_{23}a_{31}+\epsilon(3,1,2)a_{11}a_{21}a_{31}+
\epsilon(3,2,1)a_{13}a_{22}a_{31}.
\end{multlined}
\end{flalign*}
\end{document}


-
Thank you so very much, Torbjørn. I shall be so grateful to you for providing me a coherent answer. – Nisal Kevin Kotinkaduwa Sep 4 '14 at 9:14
it's often more common to place the operator at the beginning of the continued line rather than at the end of the broken line. (this does depend on the local typographic tradition; in traditional russian documents, it's placed in both locations.) – barbara beeton Sep 4 '14 at 13:07
@barbarabeeton Thanks, I can never remember which is more common. – Torbjørn T. Sep 4 '14 at 13:53

You could also just change the margin size of math environments by putting the following in your preamble:

%%  -> Define horizontal spacing for equations
\setlength{\mathindent}{length}


where you could change length to any length you prefer. For instance, if you use 1cm, it will shift the equation towards the left-hand side of the page significantly from its default position. You can also use the range type of input (e.g., 0pt plus 1pt minus 1pt) for length if you desire. Note that length can be negative as well.

-

Same code. Slightly modified with align* environment

code

 \documentclass[11pt,a4paper]{article}
\usepackage{blindtext}
\usepackage{mathtools}
\DeclareMathOperator{\sgn}{sgn}
\begin{document}
\begin{align*}
D &=\sum_{\epsilon(1,2,3)}\epsilon(1,2,3)a_{11}a_{22}a_{33}.\\
D &=\epsilon(1,2,3)a_{11}a_{22}a_{33}\\
&= +\epsilon(1,3,2)a_{11}a_{23}a_{32}\\
&= +\epsilon(2,1,3)a_{12}a_{21}a_{33}\\
&= +\epsilon(2,3,1)a_{12}a_{23}a_{31}\\
&=+\epsilon(3,1,2)a_{11}a_{21}a_{31}\\
&=+\epsilon(3,2,1)a_{13}a_{22}a_{31}.\\
\end{align*}
\end{document}


-
Sure you want all those equals signs? – Torbjørn T. Sep 4 '14 at 9:20

Try using split within the flalign:

\documentclass[11pt,a4paper]{article}
\usepackage{blindtext}
\usepackage{mathtools}
\DeclareMathOperator{\sgn}{sgn}
\begin{document}
\begin{flalign*}
D={} & \sum_{\epsilon(1,2,3)}\epsilon(1,2,3)a_{11}a_{22}a_{33}\\
\begin{split}
D={} & \epsilon(1,2,3)a_{11}a_{22}a_{33}+\epsilon(1,3,2)a_{11}a_{23}a_{32}+
\epsilon(2,1,3)a_{12}a_{21}a_{33}+\\
& \epsilon(2,3,1)a_{12}a_{23}a_{31}+\epsilon(3,1,2)a_{11}a_{21}a_{31}+
\epsilon(3,2,1)a_{13}a_{22}a_{31}
\end{split}
\end{flalign*}
\end{document}


-
Doesn't left align them though. – Torbjørn T. Sep 4 '14 at 9:16
To Greyshade, Since I just started working with LaTex, I was not aware of Split-environment. I could use this method for my work as well. Thank you for your time and knowledge. – Nisal Kevin Kotinkaduwa Sep 4 '14 at 9:18