title: Python double-asterisk ** power operator behaving unexpectedly
body: <p>I've written a function to replace scipy.interp1d by approximating the relationship between two variables (elev and MaxQ) in order to speed up my code. The equation is a fourth order polynomial. I would like the function to be able to compute Q values for single inputs and for 1D array inputs. The function is shown below.</p>
  
  <pre><code>def CalculateMaxFlow(elev):
      size=np.shape(elev)
      if size==():
          if (elev&gt;367.8): #minimum elev for flow             
              return -0.00028194553726719*elev**4+0.284027992763652*elev**3-80.3765236558431*elev**2+1900880.72298153
          else: return 0
      else:
          MaxQ=np.zeros(np.shape(elev)[0])
          for i in range(np.shape(elev)[0]):
              if (elev[i]&gt;367.8): #4th order polynomial. Not exact but okay for speeding up code              
                  MaxQ[i]= -0.00028194553726719*((elev[i])**4)+0.284027992763652*((elev[i])**3)-80.3765236558431*((elev[i])**2)+1900880.72298153
              else: MaxQ[i]= 0               
          return MaxQ
  
  elev1=380
  elev5a=380+np.zeros(5)
  elev5b=np.asarray([380,380,380,380,380])
  
  Q1=CalculateMaxFlow(elev1)
  print("Q1:"+ str(Q1))
  Q2=CalculateMaxFlow(elev5a)
  print("Q2:"+str(Q2))
  Q3=CalculateMaxFlow(elev5b)
  print("Q3:"+str(Q3))
  </code></pre>
  
  <p>The answers are as follows:</p>
  
  <pre><code>Q1:746.828053304
  Q2:[ 746.8280533  746.8280533  746.8280533  746.8280533  746.8280533]
  Q3:[ 6055481.13713196  6055481.13713196  6055481.13713196  6055481.13713196 6055481.13713196]
  </code></pre>
  
  <p>Q1 and Q2 give me the answer I expect. For some reason, Q3 does not. I'm wondering why this is. The only difference I can see in my console between eleva and elevb is that a is a float64 and b is an int32. Why would this change the result of the equation? Why then, does the result for Q1 (which is an int) also work as expected?</p>