How to neatly align long equations one below each other

Question

I have seven different equations which I want to left align.

Below is the code I am using to align the equations:

\begin{equation}
\phi_{1} \; = \; n_{20} + n_{02}
\end{equation}

\begin{equation}
\phi_{2} \; = \; (n_{20} - n_{02})^2 + 4n_{11}^2
\end{equation}

\begin{equation}
\phi_{3} \; = \; n_{30} - n_{12}^2 + 3n_{21} - n_{03}^2
\end{equation}

\begin{equation}
\phi_{4} \; = \; n_{30} + n_{12}^2 + 3n_{21} + n_{03}^2
\end{equation}

\begin{multline}
\phi_{5} \; = \; (n_{30} - 3n_{12})(n_{30} + n_{12})[(n_{30} + n_{12}^2) -3(n_{30} + n_{12})^2] + (3n_{12} - n_{03})(n_{21} + n_{03})[3(n_{30} + n_ {12})^2 - (n_{21} + n_{03})^2]
\end{multline}

\begin{equation}
\phi_{6} \; = \; (n_{20} - n_{02})[(n_{30} + n_{12}^2) - (n_{21} + n_{03})^2] + 4n_{11}(n_{30} + n_{12})(n_{21} + n_{03})
\end{equation}

\begin{equation}
\phi_{7} \; = \; (3n_{21} - n_{03})(n_{30} + n_{12})[(n_{30} + n_{12})^2 - 3(n_{21} + n_{03})^2] + (3n_{12} - n_{30})(n_{21} + n_{03})[3(n_{30} + n_{12})^2 - (n_{21} + n_{03}^2)]
\end{equation}

I want the equations to be left align and evenly spaced on each line, i.e. if an equation is too long it should go on to the next line.

(1) welcome, (2) use align to collect them all (no real need for multline, break a line in align instead. Don't use \; = \;, it is a wast of time and you end up with a setup looking uneven. — daleif, Nov 21 '16 at 11:25
(3) for left aligned equations (to the whole document) use the class option fleqn. — Guilherme Zanotelli, Nov 21 '16 at 11:31
Hi there, thanks...i don't want all the equations in the document to be left align. Just the above ones — Unknown user, Nov 21 '16 at 11:36
Equation line breaking: http://tex.stackexchange.com/questions/3782/how-can-i-split-an-equation-over-two-lines For left aligning equations: http://tex.stackexchange.com/questions/54478/how-to-left-align-a-set-of-equations — Guilherme Zanotelli, Nov 21 '16 at 11:37
@Avi Maikoo: To left-align only a group of equations, please see the answer to a recent similar question. — Bernard, Nov 21 '16 at 13:35

Mico · Accepted Answer · 2016-11-21T15:21:56.030

A single align environment seems right, plus additional line breaks for equations 5, 6, and 7; the second halves of these equations are indented (by the amount of \quad) relative to the first halves. Note that I've performed alignment on the = symbols, not full left-alignment.

\documentclass{article}
\usepackage{amsmath}
\begin{document}
\begin{align}
\phi_{1} &= n_{20} + n_{02}\\
\phi_{2} &= (n_{20} - n_{02})^2 + 4n_{11}^2\\
\phi_{3} &= n_{30} - n_{12}^2 + 3n_{21} - n_{03}^2\\
\phi_{4} &= n_{30} + n_{12}^2 + 3n_{21} + n_{03}^2\\
\phi_{5} &= (n_{30} - 3n_{12})(n_{30} + n_{12})[(n_{30} + n_{12}^2) -3(n_{30} + n_{12})^2] \notag\\
&\quad+ (3n_{12} - n_{03})(n_{21} + n_{03})[3(n_{30} + n_ {12})^2 - (n_{21} + n_{03})^2]\\
\phi_{6} &= (n_{20} - n_{02})[(n_{30} + n_{12}^2) - (n_{21} + n_{03})^2] \notag\\
&\quad+ 4n_{11}(n_{30} + n_{12})(n_{21} + n_{03})\\
\phi_{7} &= (3n_{21} - n_{03})(n_{30} + n_{12})[(n_{30} + n_{12})^2 - 3(n_{21} + n_{03})^2] \notag\\
&\quad+ (3n_{12} - n_{30})(n_{21} + n_{03})[3(n_{30} + n_{12})^2 - (n_{21} + n_{03}^2)]
\end{align}
\end{document}

score 1 · Answer 2 · answered Nov 21 '16 at 15:33

You can use align and split:

\documentclass{article}
\usepackage{amsmath}

\begin{document}

\begin{align}
\phi_{1} &= n_{20} + n_{02}
\\
\phi_{2} &= (n_{20} - n_{02})^2 + 4n_{11}^2
\\
\phi_{3} &= n_{30} - n_{12}^2 + 3n_{21} - n_{03}^2
\\
\phi_{4} &= n_{30} + n_{12}^2 + 3n_{21} + n_{03}^2
\\
\begin{split}
\phi_{5} &= (n_{30} - 3n_{12})(n_{30} + n_{12})[(n_{30} + n_{12}^2) -3(n_{30} + n_{12})^2] \\
         &\qquad+ (3n_{12} - n_{03})(n_{21} + n_{03})[3(n_{30} + n_ {12})^2 - (n_{21} + n_{03})^2]
\end{split}
\\
\begin{split}
\phi_{6} &= (n_{20} - n_{02})[(n_{30} + n_{12}^2) - (n_{21} + n_{03})^2] \\
         &\qquad+ 4n_{11}(n_{30} + n_{12})(n_{21} + n_{03})
\end{split}
\\
\begin{split}
\phi_{7} &= (3n_{21} - n_{03})(n_{30} + n_{12})[(n_{30} + n_{12})^2 - 3(n_{21} + n_{03})^2] \\
         &\qquad+ (3n_{12} - n_{30})(n_{21} + n_{03})[3(n_{30} + n_{12})^2 - (n_{21} + n_{03}^2)]
\end{split}
\end{align}

\end{document}

What's the difference with just align and \notag? The equation number in a split is vertically centered (unless the tbtags option is passed to amsmath).

How can I make align align left instead of right? – Gerardo Zinno Sep 17 '19 at 23:20 — Gerardo Zinno, Sep 17 '19 at 23:20
@GerardoZinno Isn't this left aligned? – egreg Sep 18 '19 at 08:11 — egreg, Sep 18 '19 at 08:11

How to neatly align long equations one below each other

2 Answers2