[Tex/LaTex] Force equation number to be right aligned

alignamsmathequations

I'm trying to typeset some basic equations with proper numbering. I simply want a single equation to have a right aligned number in the two column environment that I'm using. I tried three approaches, but none was satisfactory. I tried the regular equation environment, which produced a number on the next line; the \mbox approach which put the number directly next to the equation (could modify with some \; padding); and the align environment which produced no number. Specifically, I have the following

\documentclass[10pt,twocolumn]{article}
\usepackage{amsmath}

\begin{document}
\begin{equation} \label{NPV}

\textit{NPV}_{System} = P_d+&P_{a}Y\left(\frac{1}{1+r},N\right)+C_cf_{OM}Y\left(\frac{1+i}{1+r},L\right)

\end{equation}

\begin{equation} \label{NPV}

\mbox{\textit{NPV}_{System} = P_d+&P_{a}Y\left(\frac{1}{1+r},N\right)+C_cf_{OM}Y\left(\frac{1+i}{1+r},L\right)}

\end{equation}

\begin{align} \label{NPV}

\mbox{\textit{NPV}_{System} = P_d+&P_{a}Y\left(\frac{1}{1+r},N\right)+C_cf_{OM}Y\left(\frac{1+i}{1+r},L\right)}

\end{align}

\end{document}

A few questions.

How does LaTeX determine the spacing and when to break the line (first example)?
Is there a way to use \mbox to right align and not just "keep together".
Why does \align not produce an equation number in this instance?

Some background: I'm using TeXnicCenter with LuaLaTeX though I get similar results using XeLaTeX.

Best Answer

You need to fix all errors before looking at the alignment, TeX's error recovery is designed to let it continue, not to make any reasonable output at the point of the error.

Your expression is just too long to fit on one line in 2 column, here are a couple of possibilities:

\documentclass[10pt,twocolumn]{article}
\usepackage{amsmath}

\begin{document}
\begin{multline} \label{NPV}
\mathit{NPV}_{\mathrm{System}} ={}\\
 P_d+P_{a}Y(\frac{1}{1+r},N)+C_cf_{\mathrm{OM}}Y(\frac{1+i}{1+r},L)
\end{multline}

\begin{equation}\label{NPV2}
\begin{gathered} 
\mathit{NPV}_{\mathrm{System}} ={}\\
 P_d+P_{a}Y(\frac{1}{1+r},N)+C_cf_{\mathrm{OM}}Y(\frac{1+i}{1+r},L)
\end{gathered}
\end{equation}
\end{document}

Related Solutions

[Tex/LaTex] List of equations, including equation contents and caption

Since you want a cheat sheet, I'd recommend the extract package. With a slightly different MWE:

\documentclass{article}
\usepackage[
  active,
  header=false,
  copydocumentclass=true,
  generate=\jobname-Cheatsheet,
  extract-env={equation},
  extract-cmdline={synopsis},
  ]{extract} % http://ctan.org/pkg/extract
\begin{extract*}
% Items executed in both the main and extracted document
% (extract manual, section 5.1)
\usepackage{amsmath}
\end{extract*}
\begin{extract}
% Items executed only in extracted document
\def\synopsis#1{#1}
\end{extract}
\def\synopsis#1{}
\begin{document}
First Euler observed that
\synopsis{Euler's equation tying together the five fundamental constants of mathematics}%
\begin{equation}
1 + e^{i \Pi} = 0.
\end{equation}

Then, Gauss discovered the normal distribution:
\synopsis{Normal distribution}%
\begin{equation}
P(x) = \frac{1}{{\sigma \sqrt {2\pi } }}e^{{{ - \left( {x - \mu } \right)^2 } \mathord{\left/ {\vphantom {{ - \left( {x - \mu } \right)^2 } {2\sigma ^2 }}} \right. \kern-\nulldelimiterspace} {2\sigma ^2 }}}
\end{equation}

Finally, Einstein proclaimed: 
\synopsis{Equivalence of mass and energy}%
\begin{equation}
E = m C^2
\end{equation}
\end{document}

you get an original document of:

enter image description here

and an extracted document of:

\documentclass{article}
% Items executed in both the main and extracted document
% (extract manual, section 5.1)
\usepackage{amsmath}
% Items executed only in extracted document
\def\synopsis#1{#1}

\begin{document}

\synopsis{Euler's equation tying together the five fundamental constants of mathematics}%

\begin{equation}
1 + e^{i \Pi} = 0.
\end{equation}

\synopsis{Normal distribution}%

\begin{equation}
P(x) = \frac{1}{{\sigma \sqrt {2\pi } }}e^{{{ - \left( {x - \mu } \right)^2 } \mathord{\left/ {\vphantom {{ - \left( {x - \mu } \right)^2 } {2\sigma ^2 }}} \right. \kern-\nulldelimiterspace} {2\sigma ^2 }}}
\end{equation}

\synopsis{Equivalence of mass and energy}%

\begin{equation}
E = m C^2
\end{equation}

\end{document}

and:

enter image description here

This also works with your original \caption command.

[Tex/LaTex] How continue an equation next line

I suggest using the multlined environment from mathtools to break the radicand . You also can choose not to break it, but to type in medsize (~80 % of \displaystyle) with the \mediummath command from nccmath. I took the opportunity to clean your code:

\documentclass[11pt,a4paper,twocolumn]{article}
\usepackage[utf8]{inputenc}
\usepackage{mathtools, nccmath}

\begin{document}

\begin{equation*}
    \bigl| \dot{r} \bigr| =
    \sqrt{\begin{multlined}[b] -\!\bigl(e^{-t} ( \cos t + \sin t )\bigr)^2 + \\ \bigl(e^{-t} (\cos t + \sin t)\bigr)^2 + \bigl(-e^{-t}\bigr)^2 \end{multlined}}
\end{equation*}
\begin{align*}
    \bigl| \dot{r} \bigr| & =
    \sqrt{\medmath{ -\!\bigl(e^{-t} ( \cos t + \sin t )\bigr)^2 + \bigl(e^{-t} (\cos t + \sin t)\bigr)^2 + \bigl(-e^{-t}\bigr)^2}} \\
         & = \sqrt{ -\!\bigl(e^{-t} ( \cos t + \sin t )\bigr)^2 + \bigl(e^{-t} (\cos t + \sin t)\bigr)^2 + \bigl(-e^{-t}\bigr)^2}
\end{align*}

\end{document}

Best Answer

Related Solutions

[Tex/LaTex] List of equations, including equation contents and caption

[Tex/LaTex] How continue an equation next line

Related Question