title: Contour Plot in R
body: <p>I try to get a contour plot out of this. </p>
  
  <pre><code>x &lt;- seq(-250,250, by=0.005)
  y &lt;- seq(-250,250, by=0.005)
  p_x &lt;- 450+2.5*10^(-4)*(x^2+y^2)
  p_y &lt;- 450+2.5*10^(-4)*(x^2+y^2)
  z &lt;- outer(x, y, function(x, y) 0*x + 0*y)
  
  
  contour(p_x,p_y,z)
  </code></pre>
  
  <p>But it's still not working. I get the error >increasing 'x' and 'y' values expected&lt;. What may be important: z has to be a matrix made out of zeros. </p>