title: How can I take the square root of -1 using python?
body: <p>When I take the square root of -1 it gives me an error:</p>
  <blockquote>
  <p>invalid value encountered in sqrt</p>
  </blockquote>
  <p>How do I fix that?</p>
  <pre><code>from numpy import sqrt
  arr = sqrt(-1)
  print(arr)
  </code></pre>