I would like to label an equation with an arbitrary symbol, rather than a number, or letter. Is this possible?
Symbols – Labeling Equations with a Symbol in LaTeX
cross-referencingequationssymbols
Related Solutions
I would recommend using the \tag
macro to directly insert the equation number.
\documentclass{article}
\usepackage{amsmath,amssymb}
\numberwithin{equation}{section}
\begin{document}
\section{Section A}
\begin{align}
z^2&= x^2 + y^2 \\
z^2 &= x^2 + y^2 \tag{\theequation'}
\end{align}
\end{document}
As per @barbarabeeton 's answer, the '
should be \prime
as:
\documentclass{article}
\usepackage{amsmath,amssymb}
\numberwithin{equation}{section}
\begin{document}
\section{Section A}
\begin{align}
z^2&= x^2 + y^2 \\
z^2 &= x^2 + y^2 \tag{\theequation${}^\prime$}
\end{align}
\begin{equation}
z^2= x^2 + y^2
\end{equation}
\end{document}
Incidentally, the \theequation
is the way to access directly the formatted equation
counter. This works with any counter you're using, \the<counter_name>
will call the formatted counter. This is the reason \theequation
resulted in 1.1
and not just 1
, which is the value of the counter equation
.
You can do it (but only for equations in any of the amsmath
environments). But it is wrong, very wrong: you should think ahead before tweaking this way the cross reference mechanism. When you search for labels, you'll have no clue what each one refers to without first knowing what section the reference/label appears in.
\documentclass{article}
\usepackage{amsmath}
\usepackage{etoolbox}
\newcounter{dummysec}
\preto\section{\stepcounter{dummysec}}
\makeatletter
\def\label@in@display#1{%
\ifx\df@label\@empty\else
\@amsmath@err{Multiple \string\label's:
label '\df@label' will be lost}\@eha
\fi
\xdef\df@label{\thedummysec-\unexpanded{#1}}%
}
\renewcommand{\eqref}[1]{\textup{\tagform@{\ref{\thedummysec-#1}}}}
\makeatother
\begin{document}
\section*{first section}
Here is an equation
\begin{equation}\label{a1}
E=mc^2
\end{equation}
where \eqref{a1} obtained by ....
\section*{second section}
Here is another equation
\begin{equation}\label{a1}
a^2=b^2+c^2
\end{equation}
in \eqref{a1} we have ....
\end{document}
Best Answer
Perhaps something like this.