title: R Markdown to PDF and horizontal line
body: <p>With R markdown I can create an horizontal line with</p>
  
  <p><code>---</code></p>
  
  <p>This worked perfectly in RStudio on windows with Miktek.
  But I switch to Tinytex and installed Tex Live, and now <code>---</code> works on html output, but no on pdf output.</p>
  
  <p>Rendering to pdf I get:</p>
  
  <pre><code>! Missing number, treated as zero.
  &lt;to be read again&gt; 
                     \protect 
  l.96 ...enter}\rule{0.5\linewidth}{\linethickness}
                                                    \end{center} 
  
  Error: Failed to compile GSVIIIPE.tex. See https://yihui.name/tinytex/r/#debugging for debugging tips. See GSVIIIPE.log for more info.
  Ejecución interrumpida
  </code></pre>
  
  <p>I haven´t found a solution to this. Could anyone tell me is there is any solution?</p>
  
  <p>Thanks</p>