title: Contour plot for three vectors in R using rsm package
body: <p>I have the following code to construct a contour plot:</p>
  <pre><code>library(rsm)
  
  x&lt;-c(5.64,5.64,5.64,6.32,6.99,7.66,6.11,6.11,5.92,5.63)
  y&lt;-c(0.09,0.12,0.15,0.24,0.29,0.33,0.16,0.18,0.17,0.15)
  z&lt;-c(10.43,3.83,15.74,0,0,0,15.38,22.98,10.76,16.74)
  
  z.lm &lt;- lm(z ~ poly(x, y, degree=2))
  
  contour(z.lm, x ~ y)
  </code></pre>
  <p>It runs great in plain vanilla R console and I can get the graph that I need. When I try to run the very same code in RStudio, the following error pops up:</p>
  <blockquote>
  <p>Error in contour.default(z.lm, x ~ y) : no proper 'z' matrix specified</p>
  </blockquote>