Math & Science ⇒ Custom equation numbering

[magicmoose]

Hi,

I have some special equations in my document that I want to label differently to the rest. I want the to be labelled like (C1), (C2), etc. At the moment all I have managed to do is use

Code: Select all

\begin{equation*} \sum_i x_{ij}\leq 1\quad\text{for each $j=1,\ldots,J$.} \tag{C1}\end{equation*}

but I would like it to be automatic and be so that I can reference to them.

Thanks

[gmedina]

Hi,

you could define a new equation-like environment with its own counter and its appropriate representation; take a look at the following example:

Code: Select all

\documentclass{article}
\usepackage{amsmath}

\newcounter{Cequ}
\newenvironment{CEquation}
  {\stepcounter{Cequ}%
    \addtocounter{equation}{-1}%
    \renewcommand\theequation{C\arabic{Cequ}}\equation}
  {\endequation}

\begin{document}

\begin{CEquation}\label{equ:1}
  a = b.
\end{CEquation}

\begin{equation}
  c=d.
\end{equation}

\begin{CEquation}\label{equ:2}
  e = f.
\end{CEquation}

As we can see from equations \eqref{equ:1} and \eqref{equ:2}
\end{document}

[magicmoose]

Thanks a lot, thank is really nice

Can this be extended for align environments as well?

[gmedina]

Thanks a lot, thank is really nice

Can this be extended for align environments as well?

You're welcome, and yes, it can be extended; here's a little example:

Code: Select all

\documentclass{article}
\usepackage{amsmath}

\newcounter{Cequ}
\newcounter{Caux}

\newenvironment{CEquation}
  {\stepcounter{Cequ}%
    \addtocounter{equation}{-1}%
    \renewcommand\theequation{C\arabic{Cequ}}\equation}
  {\endequation}

\newenvironment{CAlign}
  {\setcounter{Caux}{\theequation}
    \setcounter{equation}{\theCequ}%
    \renewcommand\theequation{C\arabic{equation}}
    \align}
  {\endalign\setcounter{Cequ}{\value{equation}}\setcounter{equation}{\theCaux}}

\begin{document}

\begin{CEquation}\label{equ:1}
  a = b.
\end{CEquation}

\begin{equation}
  c=d.
\end{equation}

\begin{CEquation}\label{equ:2}
  e = f.
\end{CEquation}

\begin{CAlign}
  e &= f \label{equ:4} \\
  &= g  \label{equ:5}.
\end{CAlign}

\begin{equation}
  c=d.
\end{equation}

\begin{CEquation}\label{equ:6}
  e = f.
\end{CEquation}

\begin{equation}\label{equ:7}
  c=d.
\end{equation}

As we can see from equations \eqref{equ:1} and \eqref{equ:2}
\end{document}

[magicmoose]

Thanks a lot that is exactly what I what I was hoping for