3

I have the following equation:

\begin{equation}\tag{E$_{n}$}\label{E}
 f_n(x)=a
\end{equation}

When I write \eqref{E} I am referred to the equation and it is written E_n

My question is: how to be referred to the same equation and write for example E_{n-1} rather then E_n?

4
  • 3
    As a writer but more importantly as reader of scientific papers I beg you: please, please don't do that ;-) – campa Jul 26 '20 at 19:46
  • 1
    Welcome to TeX.SE! Instead of writing See Equation \eqref{E} you can also just write see Equation (E$_{n-1}$), so don't use \eqref at all if you don't want to use the tag. But I guess that would be very confusing for the reader? – Marijn Jul 26 '20 at 19:47
  • 2
    The question/intent is ill formed, as the reference is just that, a reference to the equation, which you have given a specific (non-numeric) name to. If you wish to change the formula, then this produces a dangling reference, which does not refer to anything. – oliversm Jul 26 '20 at 19:49
  • I want that when the reader click on E_{n-1}, he will be directed to the equation. Indeed, the equation is written as a function of n, and when we write E_{n-1} it will be clear for the reader how he can deduce it. – Ghizlane Jul 26 '20 at 19:53
5

You can do like this:

\documentclass{article}
\usepackage{amsmath}
\usepackage{hyperref}

\DeclareRobustCommand{\tagindex}{\ensuremath{_{\defaulttagindex}}}
\newcommand{\defaulttagindex}{n}
\DeclareRobustCommand{\indexedref}[2][n]{%
  \begingroup\def\defaulttagindex{#1}\ref{#2}\endgroup
}
\DeclareRobustCommand{\indexedeqref}[2][n]{%
  \begingroup\def\defaulttagindex{#1}\eqref{#2}\endgroup
}

\begin{document}

\begin{equation}\tag{E\tagindex}\label{E}
 f_n(x)=a
\end{equation}

We refer to~\indexedeqref{E}, but also to~\indexedeqref[n-1]{E}.

\end{document}

enter image description here

3

For this use case you can use the command \hyperref[label]{text} from the hyperref package. It creates a (clickable) link to the label with the text being shown in the document (and not the default label text).

MWE:

\documentclass{article}
\usepackage[colorlinks]{hyperref}
\usepackage{amsmath}
\begin{document}
\begin{equation}\tag{E$_{n}$}\label{E}
 f_n(x)=a
\end{equation}
See Equation \eqref{E}, also known as Equation (\hyperref[E]{E$_{n-1}$}).
\end{document}

Result:

enter image description here

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.