[Tex/LaTex] Add “Eq.” to Equation numeration but not to reference

cross-referencingequationsmath-mode

maybe I am already looking at it, but I can't see it, so I would be glad if someone can give me a short hint.

\documentclass[12pt]{scrartcl}
\usepackage[utf8]{inputenc}
\usepackage[german]{babel}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amssymb}
\renewcommand{\theequation}{\textit{Eq. \thesection.\arabic{equation}}} 

\begin{document}

\section{Vogelpohlsche Volumenformel}
\begin{equation}
n = \frac{10^{-8} F}{6 C \cdot \eta \cdot V}
\label{eq:Example}
\end{equation}

A reference to the equation \ref{eq:Example} is helpful.

\end{document}

As with this MWE, I redefined the numeration of the equation that it appears on the right as "Eq. 1.1", which works fine. But when I am referencing the equation inside text, I normally write the whole word "equation" and add the reference. Here it gives me also the abbrevation for the reference ("A reference to the equation Eq. 1.1 is helpful.").
What is the way to have the "Eq." in the numeration but not in the reference?

I want to avoid additional packages or so and I also looked up former questions like this one without seeing the solution

How to style equation label and reference differently?

Thanks for your input and have a nive day to you all!

Best Answer

What you have done so far is to change the definition of \theequation so that it contains Eq.. This means that any reference created using \label and \ref will also contain Eq., which you don't want. As described in Changing the appearance of equation numbers with amsmath, you need to modify the \tagform@ macro. Since this command contains an at character @, which is a special character for (La)TeX so you need to do this inside \makeatletter....\makeatother. The following redefinition of \tagform@ does what you want:

\makeatletter
\def\tagform@#1{\maketag@@@{(\ignorespaces\textit{Eq.~#1}\unskip\@@italiccorr)}}
\makeatother

Notice that I have used Eq.~#1 rather than Eq. #1. This just adds Eq. to the original definition of \tagform@ from amsmath.sty, which is

\def\tagform@#1{\maketag@@@{(\ignorespaces#1\unskip\@@italiccorr)}}

As the Eq. is now added by \tagform@ your redefinition of \theequation is no longer needed. You still want the equations numbered inside sections, however, so this has to be taken care of. Rather than redefining \theequation it is better to use \numberwithin{equation}{section} because this will cause the equation counter to be reset whenever the section counter is incremented.

With these changes your MWE becomes:

\documentclass[12pt]{scrartcl}
\usepackage[utf8]{inputenc}
\usepackage[german]{babel}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amssymb}
\numberwithin{equation}{section}

\makeatletter
\def\tagform@#1{\maketag@@@{(\ignorespaces\textit{Eq.~#1}\unskip\@@italiccorr)}}
\makeatother

\begin{document}

\section{Vogelpohlsche Volumenformel}
\begin{equation}
n = \frac{10^{-8} F}{6 C \cdot \eta \cdot V}
\label{eq:Example}
\end{equation}

A reference to the equation \ref{eq:Example} is helpful.

\end{document}

and the output is:

Related Solutions

[Tex/LaTex] How to mark equation number but not change the reference text

Here is a relatively simple alternate solution using flalign:

\documentclass{article}
\usepackage{amsmath}
\usepackage{mathabx}% extra symbols

\begin{document}
Here is an important equation:
\begin{flalign}\label{eq:important}
\Asterisk && S_{\text{EH}} = \int \frac{m_{p}^{2}}{2}R \sqrt{-g} d^{4}x\,.&&
\end{flalign}

Here is an unimportant equation:
\begin{equation}
  \label{eq:unimportant}
  S_{\text{M}} = \int \frac{-1}{4}F_{ab}F^{ab} \sqrt{-g} d^{4}x\,.
\end{equation}

The unimportant equation is referenced as Eq.~\eqref{eq:unimportant}.
The important equation is referenced as Eq.~\eqref{eq:important}.
\end{document}

impartant equations

Come to think of it, it works on the right side too.

\begin{flalign}\label{eq:important}
&& S_{\text{EH}} = \int \frac{m_{p}^{2}}{2}R \sqrt{-g} d^{4}x\,.&&\Asterisk
\end{flalign}

more important

[Tex/LaTex] Wrong reference to equation: Reference to section instead of equation number

I guess that you like to have something like this:

Since you not provide MWE, I haven't clue for what you need new environment. Above image of equation is obtain by fairly simpler code:

\documentclass{article}
\usepackage{mathtools}
\usepackage{array}

\begin{document}
see equation \ref{eqdesign3}

    \begin{flalign}\label{eqdesign3}
L_1 & = \frac{\mu_m N^2 A}{l}
    &   &   \begin{tabular}{>{\footnotesize $}r<{$:}>{\footnotesize}l}
         \mu_m  & Magnetic permeability [$H/m$]\\
            N   & Number of windings [-]\\
            A   & Area of the coil [$m^2$]\\
            l   & Length of the coil [$m$]
            \end{tabular}
    \end{flalign}
\end{document}

Note: the footnotesize is not an environment, sou your use is wrong.

Best Answer

Related Solutions

[Tex/LaTex] How to mark equation number but not change the reference text

[Tex/LaTex] Wrong reference to equation: Reference to section instead of equation number

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