title: Numba : cell vars are not supported
body: <p>I'd like to use numba to speed up this function:</p>
  
  <pre><code>from numba import jit
  @jit
  def rownowaga_numba(u, v):
      wymiar_x = len(u)
      wymiar_y = len(u[1])
      f = [[[0 for j in range(wymiar_y)] for i in range(wymiar_x)] for k in range(9)]
      cx = [0., 1., 0., -1., 0., 1., -1., -1., 1.]
      cy = [0., 0., 1., 0., -1., 1., 1., -1., -1.]
      w = [4./9, 1./9, 1./9, 1./9, 1./9, 1./36, 1./36, 1./36, 1./36] 
      for i in range( wymiar_x):
          for j in range (wymiar_y):
              for k in range(9):
                  up = u[i][j]
                  vp = v[i][j]
                  udot = (up**2 + vp**2)
                  cu = up*cx[k] + vp*cy[k]
                  f[k][i][j] =  w[k] + w[k]*(3.0*cu + 4.5*cu**2 - 1.5*udot)
       return f
  </code></pre>
  
  <p>Where i test it with such data:</p>
  
  <pre><code>import timeit
  import math as m
  
  u = [[m.sin(i) + m.cos(j) for j in range(40)] for i in range(1000)]
  y = [[m.sin(i) + m.cos(j) for j in range(40)] for i in range(1000)]
  
  t0 = timeit.default_timer()
  
  for i in range (10):
      f = rownowaga_pypy(u,y)
  
  dt = timeit.default_timer() - t0
  print('loop time:', dt)
  </code></pre>
  
  <p>And im getting this error:</p>
  
  <pre><code>    Traceback (most recent call last):
    File "C:\Users\Ricevind\Desktop\PyPy\Skrypty\Rownowaga.py", line 29, in &lt;module&gt;
      f = rownowaga_pypy(u,y)
    File "C:\pyzo2014a\lib\site-packages\numba\dispatcher.py", line 171, in _compile_for_args
      return self.compile(sig)
    File "C:\pyzo2014a\lib\site-packages\numba\dispatcher.py", line 348, in compile
      flags=flags, locals=self.locals)
    File "C:\pyzo2014a\lib\site-packages\numba\compiler.py", line 637, in compile_extra
      return pipeline.compile_extra(func)
    File "C:\pyzo2014a\lib\site-packages\numba\compiler.py", line 356, in compile_extra
      raise e
    File "C:\pyzo2014a\lib\site-packages\numba\compiler.py", line 351, in compile_extra
      bc = self.extract_bytecode(func)
    File "C:\pyzo2014a\lib\site-packages\numba\compiler.py", line 343, in extract_bytecode
      bc = bytecode.ByteCode(func=self.func)
    File "C:\pyzo2014a\lib\site-packages\numba\bytecode.py", line 343, in __init__
      raise NotImplementedError("cell vars are not supported")
  NotImplementedError: cell vars are not supported
  </code></pre>
  
  <p>I'm mostly interested in the meaning of "cell vars are not supported" as Google returns no meaning results.</p>