title: TypeError: 'AffineScalarFunc' object is not iterable
body: <p>I defined a function such as:</p>
  
  <pre><code>def ucos(a):
      temp=[umath.cos(i) for i in a]
      return unumpy.uarray([unumpy.nominal_values(i) for i in temp], [unumpy.std_devs(i) for i in temp])
  </code></pre>
  
  <p>But when I try to iterate over it with a for loop:</p>
  
  <pre><code>for j in range(len(Beta)):
      if Beta[j]&lt;pi/2.:
         Radius.append((Diam_meas[j]/2.)*(ucos((pi/2)-Beta[j]))**(-1)*10**(-9))
      else:
         Radius.append((Diam_meas[j]/2.)*10**(-9))
  </code></pre>
  
  <p>it gives me the error:</p>
  
  <pre><code>TypeError: 'AffineScalarFunc' object is not iterable
  </code></pre>
  
  <p>Do you have any idea on why ucos function is not iterable? How to make it iterable?
  thx!</p>