title: Global name 'col2im_6d_cython' is not defined, CS231n
body: <p>I'm following CS231n and met a problem when doing assignment2: ConvolutionalNetworks: <code>global name 'col2im_6d_cython' is not defined</code>.</p>
  
  <p>I think the problem was due to a failure in importing functions from <code>im2col_cython.pyx</code>, which used cython. </p>
  
  <p>I've installed Xcode 7.3.1, as shown below, but the problem was still not solved.</p>
  
  <p><a href="https://i.stack.imgur.com/1xlwH.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/1xlwH.png" alt="Results of &quot;gcc -v&quot;"></a></p>
  
  <p>I'm running the ipynb files in Jupyter from Anaconda. There is a related <a href="https://www.reddit.com/r/cs231n/comments/44r6ay/a2_convnets_problem_with_sandwich_layer_col2im_6d/" rel="nofollow noreferrer">discussion on reddit</a>, but unfortunately the solution here was for Windows, not Mac OS X.</p>
  
  <p>Thank you for your time.</p>