[Tex/LaTex] the difference between \eqref and \ref

cross-referencingequations

Is there any difference between \eqref and \ref? I used both of them in my document using the package classicthesis and saw no difference in the result. Is there any specific situation in which I should use \eqref or \ref?

Best Answer

The command \ref is defined in the LaTeX Kernel. The command \eqref is defined by amsmath. In the documentation of amsmath you will find the explanation in section 3.11.2 Cross references to equation numbers.

\eqref puts brackets around the reference number. It's also places the references in in \upshape (or \textup), to match the equation reference exactly (Thanks to Werner). This is shown in the example below.

\documentclass{article}
\usepackage{amsmath}

\begin{document}
\begin{equation}
a^2+b^2=c^2\label{eq:1}
\end{equation}

\verb+\eqref{eq:1} vs \ref{eq:1}+: \eqref{eq:1} vs \ref{eq:1}

\verb+\textit{\eqref{eq:1} vs \ref{eq:1}}+: \textit{\eqref{eq:1} vs \ref{eq:1}}

\end{document}

enter image description here

If you use the package classicthesis, you must load amsmath before. Because the package classicthesis loads the package hyperref. However the package itself doesn't change the format of the output.

Related Solutions

[Tex/LaTex] Using achemso package, can’t reference equations with \label and \ref

The problem comes down to a change in cleveref, which now seems to have a load order requirement with amsmath which was not previously the case. With the minimal example

\documentclass{article}
\usepackage{cleveref}
\usepackage{amsmath}

\begin{document} 

\begin{equation}
\label{eq:structprop}
a
\end{equation} 

\cref{eq:structprop}

\end{document}

The issue is visible with the current cleveref release, but did not occur previously.

[Tex/LaTex] the difference between \notag and \nonumber in align environment

Both are commands to switch off equation numbering. \nonumber is a kernel command, defined as:

\def\nonumber{\global\@eqnswfalse}

so you can use \nonumber without loading additional packages. \notag is defined in the amsmath package as \nonumber:

\newcommand{\notag}{\nonumber}

and then amsmath redefines \nonumber in the following way:

\renewcommand{\nonumber}{%
  \if@eqnsw
    \ifx\incr@eqnum\@empty \addtocounter{equation}\m@ne \fi
  \fi
  \let\print@eqnum\@empty \let\incr@eqnum\@empty
  \global\@eqnswfalse
}

which is a more safe version to use with amsmath. The definition of \notag will make \notag expand to the definition of \nonumber at the place of appearance, which is after \nonumber has been redefined. Hence (of course, when amsmath is used) the effect of both is the same.

Thanks to egreg and tohecz for their corrections.

Best Answer

Related Solutions

[Tex/LaTex] Using achemso package, can’t reference equations with \label and \ref

[Tex/LaTex] the difference between \notag and \nonumber in align environment

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