title: numpy.random.exponential(scale=1.0) returns numbers greater than 1
body: <p>Unless I've gone completely insane, the documentation for numpy.random.exponential()</p>
  
  <p><a href="http://docs.scipy.org/doc/numpy/reference/generated/numpy.random.exponential.html" rel="nofollow">http://docs.scipy.org/doc/numpy/reference/generated/numpy.random.exponential.html</a></p>
  
  <p>suggests that setting the scale parameter to 1.0 should guarantee that function calls return a number between 0.0 and 1.0, since it is only defined for x > 0. </p>
  
  <p>I've graphed it on wolfram alpha to verify I'm not going insane and it does range from 0 to 1. </p>
  
  <p><a href="https://www.wolframalpha.com/input/?i=graph+exp(-x)+from+-1+to+10" rel="nofollow">https://www.wolframalpha.com/input/?i=graph+exp(-x)+from+-1+to+10</a></p>
  
  <p>I also tried both numpy.random.exponential() since the default argument is 1.0 and numpy.random.standard_exponential(), but both sometimes give me values greater than 1. </p>
  
  <p>I feel like I've made some silly mistake in my understanding but cannot find it. Any help would be greatly appreciated. </p>
  
  <p>Example code that I ran:</p>
  
  <pre><code>import numpy as np
  print np.random.exponential(scale=1.0)
  </code></pre>
  
  <p>Example returned value:</p>
  
  <pre><code>1.56783951494
  </code></pre>