title: Overflow in exp in scipy/numpy in Python?
body: <p>What does the following error:</p>
  
  <pre><code>Warning: overflow encountered in exp
  </code></pre>
  
  <p>in scipy/numpy using Python generally mean?  I'm computing a ratio in log form, i.e. log(a) + log(b) and then taking the exponent of the result, using exp, and using a sum with logsumexp, as follows:</p>
  
  <pre><code>c = log(a) + log(b)
  c = c - logsumexp(c)
  </code></pre>
  
  <p>some values in the array b are intentionally set to 0. Their log will be -Inf.</p>
  
  <p>What could be the cause of this warning?  thanks.</p>