title: Strange basic computation issue with numpy.int64 and/or numpy.float64?
body: <p>I am getting a very weird and unexpected ERROR from python-numpy </p>
  
  <p>I am working with the following libraries:</p>
  
  <pre><code>import os, glob, string, math, csv, json
  import datetime as dt
  import numpy as np
  import scipy as sci
  import pandas as pd
  import matplotlib.pyplot as plt
  import feedparser as fp
  import cPickle as pickle
  import networkx as nx
  from urllib2 import urlopen
  import statsmodels.formula.api as sm
  import patsy
  </code></pre>
  
  <p>The following code:</p>
  
  <pre><code>n,k = 2643605051, 648128.068241
  print n,type(n)
  print k, type(k)
  nkvar = (k + 1)*(n + 2)/( (n+2) * (n+1)**2 )
  print nkvar
  
  n = np.int64(n)
  k = np.float64(k)
  print n,type(n)
  print k, type(k)
  nkvar = (k + 1)*(n + 2)/( (n+2) * (n+1)**2 )
  print nkvar
  </code></pre>
  
  <p>Yields:</p>
  
  <pre><code>2643605051 &lt;type 'int'&gt;
  648128.068241 &lt;type 'float'&gt;
  9.27402694708e-14
  2643605051 &lt;type 'numpy.int64'&gt;
  648128.068241 &lt;type 'numpy.float64'&gt;
  -0.00383719008751
  </code></pre>
  
  <p>The second answer is OBVIOUSLY wrong!  Could someone please help me understand what is going on?</p>