# How does one break columns in LaTeX?

Some time ago, I had a problem with \columnbreak. This question solved it. But now the problem has come again, and this time the linked solution doesn't work. Here is the code:

\documentclass{beamer}
\usepackage{amsmath,amssymb,amsfonts}
\newcommand{\R}{\mathbb{R}}
\newcommand{\wg}{\omega}
\newcommand{\J}{\mathbb{J}}
\usepackage{graphicx,multicol}

\begin{document}
\begin{frame}
\frametitle{Esempi di campi Hamiltoniani}
\begin{exampleblock}{Varietà simplettica standard}
In $(\R^{2n},\wg_0)$, i campi Hamiltoniani sono esattamente quelli della forma:
$X_H(x)=\J\grad H(x).$
\end{exampleblock}
\onslide<2>
\begin{exampleblock}{Sulla sfera}
\twocolumn
Su $S^2$ consideriamo la forma di qualche diapositiva fa e la funzione indotta per restrizione da $z:\R^3\to\R$. Il campo $H_z$ è tangente alle circonferenze orizzontali su $S^2$. \columnbreak\linebreak
\rule{3cm}{3cm}{3cm}
\end{exampleblock}
\end{frame}
\end{document}


Output:

No column break there. Yet I did add the \linebreak. And neither \par, \\ or \newline do, nor a blank line do anything. The only effective thing is wrapping it all in \begin{multicols}{2}…\end{multicols}. So how does one insert a column break in plain LaTeX, without multicol, if \columbreak doesn't work?

• you're probably better off using two side-by-side minipages. and, by the way, since amssymb loads amsfonts, you don't need to do that again. – barbara beeton Nov 12 '15 at 21:09
• Yeah, I really need to learn what a minipage is :). – MickG Nov 12 '15 at 21:10

No, \twocolumn will definitely not work. You need a \parbox (or minipage), with a small trick for aligning the image at the top.

The space reserved in these cases is usually variable across columns, so no “automated” solution will work. Slides need to be crafted manually anyway, so it's not a big problem.

\documentclass{beamer}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage[italian]{babel}
\usepackage{amssymb}

\newcommand{\R}{\mathbb{R}}
\newcommand{\wg}{\omega}
\newcommand{\J}{\mathbb{J}}
\usepackage{graphicx,multicol}

\begin{document}

\begin{frame}
\frametitle{Esempi di campi Hamiltoniani}

\begin{exampleblock}{Varietà simplettica standard}
In $(\R^{2n},\wg_0)$, i campi Hamiltoniani sono esattamente quelli della forma:
$X_H(x)=\J\grad H(x).$
\end{exampleblock}

\pause

\begin{exampleblock}{Sulla sfera}
\parbox[t]{.6\linewidth}{
Su $S^2$ consideriamo la forma di qualche diapositiva fa e la funzione indotta
per restrizione da $z:\R^3\to\R$. Il campo $H_z$ è tangente alle circonferenze
orizzontali su $S^2$.

Are you really sure that \wg is more readable than \omega? Maybe slightly faster to type, but it has no meaning, so you're likely to forget what it means in a month or two.
• w looks like ω, and g stands for Greek. No chance of forgetting that. And the time I spare typing \wg instead of \omega is decidedly important when taking notes, which is where I use the package I wrote in which this command is. Besides trust me, I am so used to typing like that that I end up typing \wg on Math SE too, so no chance of forgetting :). The mapping is abgdezhqiklmnjoprstufxyw to the greek alphabet in the right order. And… déjà-vu :). – MickG Nov 12 '15 at 21:54