title: To apprixmate a multivariate function with a neural network, which activation function to use?
body: <p>I would like to approximate a multi-variate function that looks like this:</p>
  <p><a href="https://i.stack.imgur.com/VJ1nn.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/VJ1nn.png" alt="enter image description here" /></a></p>
  <p>I was thinking of using the Sigmoid function to keep a continuous output, but I am wondering if there exist a better choice.</p>
  <p>Thanks</p>