title: check if two numeric values have same sign in numpy (+/-)
body: <p>currently i am using numpy.logical_or with numpy.logical_and to check if elements of two arrays have same sign. Was wondering if there is already a ufunc  or a more effective method that will achieve this. My current solutions is here</p>
  
  <pre><code>a = np.array([1,-2,5,7,-11,9])
  b = np.array([3,-8,4,81,5,16])
  out = np.logical_or(
                      np.logical_and((a &lt; 0),(b &lt; 0)), 
                      np.logical_and((a &gt; 0),(b &gt; 0))
                                               )
  </code></pre>
  
  <p>edit//
  output</p>
  
  <pre><code>out
  Out[51]: array([ True,  True,  True,  True, False,  True], dtype=bool)
  </code></pre>