title: pow() implementation in cmath and efficient replacement
body: <p>I've read that <code>cmath</code> calculates <code>pow(a,b)</code> by performing <code>exp(b*log(a))</code>. This should not be used when <code>b</code> is an integer, since it slows down calculations a lot. What alternatives are there when</p>
  
  <ol>
  <li>calculating <em>a lot</em> of successive <code>pow()</code>s with the same constant <code>a</code></li>
  <li>it is known beforehand that <code>b</code> will <strong>definitely</strong> be an integer?</li>
  </ol>
  
  <p>I am looking for fast alternatives which are efficient in these particular scenarios.</p>