# Enumerate a list of equations

Consider the following MWE:

\documentclass[12pt,a4paper]{article}

\usepackage[fleqn]{amsmath}
\usepackage{amssymb}
\usepackage{amsthm}
\usepackage{enumitem}

\newcommand{\C}{\mathbb{C}}
\begin{document}

\begin{enumerate}[label=(\roman*)]
\itemsep -0.2em
\item \begin{equation*}
e^z =  \sum_{n=0} z^n / n!
\end{equation*}
\item \begin{equation*}
\sin z = \sum_{n=0} (-1)^n z^{2n+1}/ (2n+1)!
\end{equation*}
\item \begin{equation*}
\cos z = \sum_{n=0} (-1)^n z^{2n}/ 2n! \\
\text{which converges } \forall \ z \in \C
\end{equation*}
\item \begin{equation*}
\log_e (1 - z) = - \sum_{n=1} z^n/n
\end{equation*}
\item \begin{equation*}
(1 - z)^{-1} = \sum_{n=0} z^n \\
\text{which converges for } |z| < 1
\end{equation*}
\end{enumerate}

\end{document}


How can I get the enumeration numbers (i, ii, etc) on the same line as the equations?

• Why do you use equation* if you want the behavior of equation? Apr 21, 2017 at 17:32
• I want the enumeration to do the labeling on the left, equation won't do that. Further, I don't want the equations labeled as such, but enumerated. Apr 21, 2017 at 17:43
• It will do it! LaTeX is very flexible. Btw: If you use enumitem never mess with \itemsep manually. Apr 21, 2017 at 17:44
• @AthenaWidget And now please admit that equation will do it :) Apr 21, 2017 at 17:51

I don't see anything in your questions, which couldn't be done using equation.

\documentclass[12pt,a4paper]{article}

\usepackage[fleqn]{amsmath}
\usepackage{amssymb}
\usepackage{amsthm}
\newcommand{\C}{\mathbb{C}}

\newcounter{dummy}

\makeatletter
\newcommand{\leqnomode}{\tagsleft@true}
\makeatother

\begin{document}

$$normalequation$$

\bgroup
\leqnomode
\setcounter{dummy}{\theequation}
\renewcommand{\theequation}{\roman{equation}}%

$$e^z = \sum_{n=0} z^n / n!$$
$$\sin z = \sum_{n=0} (-1)^n z^{2n+1}/ (2n+1)!$$
$$\cos z = \sum_{n=0} (-1)^n z^{2n}/ 2n! \\ \text{which converges } \forall \ z \in \C$$
$$\log_e (1 - z) = - \sum_{n=1} z^n/n$$
$$(1 - z)^{-1} = \sum_{n=0} z^n \\ \text{which converges for } |z| < 1$$

\setcounter{equation}{\thedummy}
\egroup

\bgroup
\leqnomode
\setcounter{dummy}{\theequation}
\renewcommand{\theequation}{\roman{equation}}%

$$e^z = \sum_{n=0} z^n / n!$$
$$\sin z = \sum_{n=0} (-1)^n z^{2n+1}/ (2n+1)!$$
$$\cos z = \sum_{n=0} (-1)^n z^{2n}/ 2n! \\ \text{which converges } \forall \ z \in \C$$
$$\log_e (1 - z) = - \sum_{n=1} z^n/n$$
$$(1 - z)^{-1} = \sum_{n=0} z^n \\ \text{which converges for } |z| < 1$$

\setcounter{equation}{\thedummy}
\egroup

$$normal equation$$

\end{document}


\leqnomode is borrowed from Tag placing with amsmath

• Probably the spacing would be better with gather or align. Apr 21, 2017 at 19:00
• @Bernard Probably. Would you like to add an answer? Apr 21, 2017 at 19:24
• No, I think I'll add a ‘real’ enumerate answer instead. You can update your answer if you wish. Perhaps you might add details on how to maintain the current equation counter. Apr 21, 2017 at 19:28

A solution with the enumerate environment:

\documentclass[12pt, a4paper]{article}

\usepackage[fleqn]{mathtools}
\usepackage{amssymb}
\usepackage{amsthm}
\usepackage{enumitem}

\newcommand{\C}{\mathbb{C}}

\begin{document}

\begin{enumerate}[label=(\roman*), leftmargin=*, itemsep=0.4ex, before={\everymath{\displaystyle}}]%
\item $e^z = \sum_{n=0} z^n / n!$ \label{eq-1}
\item $\sin z = \sum_{n=0} (-1)^n z^{2n+1}/ (2n+1)!$\label{eq-2}
\item \begin{aligned}[t] & \cos z = \sum_{n=0} (-1)^n z^{2n}/ 2n!\\ & \text{which converges \forall \ z \in \C } \label{eq-3} \end{aligned}
\item $\log_e (1 - z) = - \sum_{n=1} z^n/n$ \label{eq-4}
\item \begin{aligned}[t] & (1 - z)^{-1} = \sum_{n=0} z^n ,\\ &\text{which converges for |z| < 1 } \end{aligned} \label{eq-5}
\end{enumerate}
It is easy to prove eq. \ref{eq-3}.

\end{document}


A solution based on the TeXnician's comment.

\documentclass[12pt,a4paper]{article}

\usepackage[leqno, fleqn]{amsmath}
\usepackage{amssymb}
\usepackage{ mathtools }

\newcommand{\C}{\mathbb{C}}

\makeatletter
\newcommand{\leqnomode}{\tagsleft@true}
\newcommand{\reqnomode}{\tagsleft@false}
\makeatother

\newtagform{Alph}[\renewcommand{\theequation}{\Alph{equation}}]()
\newtagform{roman}[\renewcommand{\theequation}{\roman{equation}}]()
\newtagform{scroman}[\renewcommand{\theequation}{\scshape\roman{equation}}]
[]

\begin{document}

\usetagform{roman}
\begin{align}
&e^z =  \sum_{n=0} z^n / n! \\
&\sin z = \sum_{n=0} (-1)^n z^{2n+1}/ (2n+1)! \\
&\cos z = \sum_{n=0} (-1)^n z^{2n}/ 2n! \text{   which converges }
\forall \ z \in \C  \\
&\log_e (1 - z) = - \sum_{n=1} z^n/n \\
&(1 - z)^{-1} = \sum_{n=0} z^n  \text{   which converges for } |z| < 1
\end{align}

%\setcounter{equation}{0}
\end{document}


References:

Switch between leqno and reqno options (of amsmath) in the same document

How to change numbers to roman numerals in align environment

• Something occurred to me, what if I wanted the equations enumerated and labeled. I think @samcarter has the better answer. Apr 24, 2017 at 15:05