Per cent symbol in R-code chunk knitr

Question

I am using the knitr-package (version 1.10.5) to produce latex beamer slides. The per cent symbol in the matrix multiplication operator %*% is interpreted as a LaTeX comment.

The knitr chunk looks the following

\begin{frame}
<<echo=TRUE,eval=TRUE>>=
x<-1:10
y<-1:10
x%*%y
@
\end{frame}

and this is the LaTeX code I get

\begin{frame}

\begin{knitrout}\footnotesize
\definecolor{shadecolor}{rgb}{0.969, 0.969, 0.969}\color{fgcolor}\begin{kframe}
\begin{alltt}
\hlstd{x}\hlkwb{<-}\hlnum{1}\hlopt{:}\hlnum{10}
\hlstd{y}\hlkwb{<-}\hlnum{1}\hlopt{:}\hlnum{10}
\hlstd{x}\hlopt{%*%}\hlstd{y}
\end{alltt}
\begin{verbatim}
##      [,1]
## [1,]  385
\end{verbatim}
\end{kframe}
\end{knitrout}

\end{frame}

Answer 1

I found the solution. The amendment [fragile] helps a lot:

\begin{frame}[fragile]
<<echo=TRUE,eval=TRUE>>=
x<-1:10
y<-1:10
x%*%y
@
\end{frame}