title: Python: What is the difference between math.exp and numpy.exp and why do numpy creators choose to introduce exp again
body: <p><code>exp</code> means exponential function</p>
  
  <p><code>exp</code> in <code>math module</code>: <a href="https://docs.python.org/2/library/math.html" rel="noreferrer">https://docs.python.org/2/library/math.html</a></p>
  
  <p><code>exp</code> in <code>numpy module</code>: <a href="http://docs.scipy.org/doc/numpy/reference/generated/numpy.exp.html" rel="noreferrer">http://docs.scipy.org/doc/numpy/reference/generated/numpy.exp.html</a></p>
  
  <p>Why do <code>numpy</code> creators introduce this function again?</p>