title: Drawing non-intersecting circles
body: <p>I'm trying to plot two non-intersecting touching circles, but I think I'm missing something quite basic...</p>
  
  <pre><code>jpeg(file="test.jpg")
  diam &lt;- sqrt (2)
  plot (c(-1,1), c(1,-1), xlim=c(-5,5), ylim=c(-5,5))
  
  symbols (c(-1,1), c(1,-1), circles=c(diam,diam), add=TRUE, inches=FALSE)
  dev.off()
  </code></pre>
  
  <p>Can anyone explain to me why these circles overlap?</p>
  
  <p><img src="https://i.stack.imgur.com/QKRbF.jpg" alt="alt text"></p>