[Tex/LaTex] reference to equation from other lecture in class beamer

beamercross-referencing

I'm using the class beamer to prepare lectures. I want to make a
reference to a formula given in last week's lecture, but I get only
question marks.

Example input:

\documentclass[handout]{beamer}

\includeonlylecture{week 2}

\begin{document}

\lecture{lecture 1}{week 1}
\begin{frame}
  \begin{equation}
    \label{eq:test}
      1=1
  \end{equation}
\end{frame}

\lecture{lecture 2}{week 2}
\begin{frame}
  \begin{equation}
    \label{eq:test2}
      2=2
  \end{equation}
equation(\ref{eq:test}) and (\ref{eq:test2})
\end{frame}

\end{document}

equation number 1 is correctly counted when calculating the number for
the second equation, but I did not manage to get acces to \ref{eq:test}.

Any hints?

thanks

Martin

Best Answer

Assuming you compiled the slides from week one with the jobname "test", you could do

\RequirePackage{xr-hyper}
\documentclass[handout]{beamer}

\externaldocument{test}
\includeonlylecture{week 2}

\begin{document}

\lecture{lecture 1}{week 1}
\begin{frame}
  \begin{equation}
    \label{eq:test}
      1=1
  \end{equation}
\end{frame}

\lecture{lecture 2}{week 2}
\begin{frame}
  \begin{equation}
    \label{eq:test2}
      2=2
  \end{equation}
equation (\ref{eq:test}) and (\ref{eq:test2})
\end{frame}

\end{document}

Related Solutions

[Tex/LaTex] Extract Section number from Equation reference

You can do this easily with the help of the refcount (to turn the reference number into a string), xstring (to extract the number before and after the dot), and engord (to get the desired format as ordinal number) packages.

In the following example, I defined the commands \SecNum and \EqNum; the first one gives the section number of the reference and the second one gives the equation number in ordinal notation and turns it into a hyperlink to the given equation:

\documentclass[10pt,a4paper,fleqn]{article}
\usepackage{amsmath}
\usepackage{refcount}
\usepackage{xstring}
\usepackage{engord}
\usepackage{xspace}
\usepackage{lipsum}
\usepackage{hyperref}

\hypersetup{colorlinks}
\numberwithin{equation}{section}
\setlength{\parindent}{0pt}

\newcommand\equ{}
\newcommand\EqNum[1]{%
  \StrBehind{\getrefnumber{#1}}{.}[\equ]%
  \hyperref[#1]{\engordnumber{\equ}\xspace}%
}
\newcommand\SecNum[1]{%
  \StrBefore{\getrefnumber{#1}}{.}\xspace%
}

\begin{document}

\section{Start}
\lipsum[1]

\section{Halfway}

The equation \eqref{ThisOne} is the \EqNum{ThisOne}~Equation in Section \SecNum{ThisOne}.

\section{End}

A famous formula:

\begin{equation}
x_1, x_2 = \frac{ -b \pm \sqrt{b^2 - 4ac} }{ 2a }
\end{equation}

And another one:

\begin{equation}
\sin^2(\varphi) + \cos^2(\varphi) = 1
\label{ThisOne}
\end{equation}

\end{document}

enter image description here

I added \xspace from the xspace package to take care of proper spacing.

[Tex/LaTex] Reference a slide in Beamer

Place a label to the frame you want to cross-reference and then use \ref:

\documentclass[]{beamer}
\usetheme{Madrid}

\usenavigationsymbolstemplate{}

\title{Main Title} 
\author{Jane Doe}
\institute{University A}
\date{\today}

\begin{document}

\begin{frame}
\titlepage % Print the title page as the first slide
\end{frame}

\begin{frame}
\frametitle{First Page}
\begin{exampleblock}{Example}
This is an example which will be used later.
\end{exampleblock}
\end{frame}

\begin{frame}[label={important}]
\frametitle{Second Page}
\begin{itemize}
\item Item 1
\item Item 2
\end{itemize}
\end{frame}

\begin{frame}
\frametitle{Third Page}
\begin{itemize}
\item In this slide, we are going to use the sample example on slide~\ref{important}.
\end{itemize}
\end{frame}

\end{document}

Best Answer

Related Solutions

[Tex/LaTex] Extract Section number from Equation reference

[Tex/LaTex] Reference a slide in Beamer

Related Question