\cal messes up the math mode

Question

How come when I use this code with beamer

\begin{block}{Misadjustment}
 $$ \cal{M} = \frac{1-\lambda}{2}\sigma_v^2 M + \frac{1}{2(1-\lambda)}tr[\mathbf{RQ}] $$
\end{block}

results in this:

enter image description here

But when I remove the \cal, the equation is displayed correctly.

\cal is a font, so you can also write your equation with $${\cal M}=\frac{1-\lambda}{2} ...$$ — lvaneesbeeck, Dec 26 '13 at 00:32

score 12 · Accepted Answer · edited Apr 13 '17 at 12:35

You need to use \mathcal, which takes an argument, not \cal:

enter image description here

\documentclass{beamer}% http://ctan.org/pkg/beamer
\begin{document}
\begin{frame}
\begin{block}{Misadjustment}
\[
  \mathcal{M} = \frac{1-\lambda}{2}\sigma_v^2 M + \frac{1}{2(1-\lambda)}tr[\mathbf{RQ}]
\]
\end{block}
\end{frame}
\end{document}

The use is similar to your font switching macro \mathbf. Also note the use of \[...\] to denote a display math equation rather than the TeX $$...$$ notation. For more on this, see Why is \[ … \] preferable to $$?.

\cal messes up the math mode

1 Answers1