title: Python: Why cmath.exp(1j*math.pi) gives the answer -1+1.2246063538223773e-16j but not simply -1
body: <p>So I tried to check <a href="http://en.wikipedia.org/wiki/Euler%27s_identity" rel="nofollow">Euler's İdentity</a> in python console:</p>
  
  <pre><code>import math
  import cmath
  cmath.exp(1j*math.pi)
  </code></pre>
  
  <p>and result was:</p>
  
  <pre><code>-1+1.2246063538223773e-16j
  </code></pre>
  
  <p>Shouldn't it be just -1.</p>