# Equation number is not appeared using align environment

\usepackage{times}
\usepackage{graphicx}
\usepackage{algorithm}
\usepackage{algorithmic}
\usepackage[nointegrals]{wasysym}
\usepackage{amsmath}
\usepackage{pseudocode}
\usepackage{rotating}


I've used the following code to generate a formula with equation number, nevertheless, the equation number is not appeared:

\begin{align}
T(n) & \leq 2(c\lfloor n/2 \rfloor \lg( \lfloor n/2 \rfloor )) + n \\
T(n) & \leq 2(cn/2) \lg(n/2) + n \\
T(n) & = cn (\lg n - 1) + n \\
T(n) & \leq cn \lg n
\end{align}


The packages used are as above.

EDIT:

The culprit is found if I put the following line that uses indent command before invoking align command:

\indent $ratio_{actual}$ = ground truth ratio between width and length of the box \nonumber \\


I'm still curious how I would still use the align command while preserving the indent command.

• No problems here, assuming the article class. – Paul Gessler Apr 12 '14 at 22:30
• it'd be great if you could make your snippets into a complete MWE - not only will it help the community, but it will also help you to diagnose the problem :) – cmhughes Apr 12 '14 at 22:35
• Did you try using align or aligned inside equation environment? – MattAllegro Apr 13 '14 at 1:21
• I found the culprit as the above EDIT, but still hunting for the remedy. – alfa_80 Apr 13 '14 at 2:36
• @PaulGessler: Yes, it is an article class. – alfa_80 Apr 13 '14 at 2:37

If you remove the \nonumber \\ as I have commented out below you get the numbering:

## Notes:

• I am not sure what purpose the \nonumber \\ was to serve. I don't think there should be a need to use a \\ outside of a tabular or math environment.
• Also, I added a \mathrm to the ratio and actual as I don't think that is more appropriate.
• Have also removed the \indent as I am not sure as to why you need it. But, it does not effect the numbering of the align environment.

## Code:

\documentclass{article}

\usepackage{times}
\usepackage{graphicx}
\usepackage{algorithm}
\usepackage{algorithmic}
\usepackage[nointegrals]{wasysym}
\usepackage{amsmath}
\usepackage{pseudocode}
\usepackage{rotating}

\begin{document}

$\mathrm{ratio}_{\mathrm{actual}}$ = ground truth ratio between width and length of the box  %\nonumber \\
\begin{align}
T(n) & \leq 2(c\lfloor n/2 \rfloor \lg( \lfloor n/2 \rfloor )) + n \\
T(n) & \leq 2(cn/2) \lg(n/2) + n \\
T(n) & = cn (\lg n - 1) + n \\
T(n) & \leq cn \lg n
\end{align}
\end{document}

• Thanks anyway, I found another way of resolving it, but this is helpful too. – alfa_80 Apr 13 '14 at 4:36
• @Shah: You should post an answer then. You probably are not the last person to encounter this problem so posting an answer will be helpful. – Peter Grill Apr 13 '14 at 5:05
• I've added but it needs two days for it to be approved. Even so, I'll give a more concrete one. Thanks for reminding me :-) – alfa_80 Apr 13 '14 at 5:34

I found out that omitting \nonumber command in the \indent command solves the issue. So, the resultant fix of it is as below:

\usepackage{times}
\usepackage{graphicx}
\usepackage{algorithm}
\usepackage{algorithmic}
\usepackage[nointegrals]{wasysym}
\usepackage{amsmath}
\usepackage{pseudocode}
\usepackage{rotating}

\indent $ratio_{actual}$ = ground truth ratio between width and length of the box \\

\begin{align}
T(n) & \leq 2(c\lfloor n/2 \rfloor \lg( \lfloor n/2 \rfloor )) + n \\
T(n) & \leq 2(cn/2) \lg(n/2) + n \\
T(n) & = cn (\lg n - 1) + n \\
T(n) & \leq cn \lg n
\end{align}

• The \indent command is doing nothing here (you never need to use \indent in LaTeX) Never use \\  at the end of a paragraph, and never leave a blank line before a math display such as align. Also when posting questions and answers please always post complete documents as in Peter's answer. – David Carlisle Apr 13 '14 at 15:17