title: How to plot multivariate function in R
body: <p>I am trying to plot the following function:<a href="https://i.stack.imgur.com/UqEBa.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/UqEBa.png" alt="enter image description here"></a></p>
  
  <p>This is what I have currently tried:</p>
  
  <pre><code>curve(7*x*y/( e^(x^2+y^2)))
  </code></pre>
  
  <p>But I get the following error:</p>
  
  <p><a href="https://i.stack.imgur.com/RvaNr.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/RvaNr.png" alt="enter image description here"></a></p>