title: Cython return tuple within cdef?
body: <p>Hi I am trying to convert a python code into cython in order to speed up its calculation. I am trying to return multiple arrays within the cython code from a <code>cdef</code> to <code>cpdef</code>. Based on classical C, I could either use a pointer or a tuple. I decide to use tuple because the size varies. I know the following code doesn't work, any help? Thank you!</p>
  
  <pre><code>import numpy as np
  cimport numpy as np
  
  cdef tuple funA(double[:] X, double[:] Y): 
      cdef int nX, nY, i
      nX = len(X)
      nY = len(Y)
  
      for i in range(nX):
          X[i] = X[i]*X[i]
  
      for i in range(nY):
          Y[i] = Y[i]*Y[i]
  
      return X,Y
  
  cpdef Run(double[:] X, double[:] Y)
      cdef Tuple1, Tuple2 = funA(X,Y)
  
      # Do some calculation with Tuple1 and Tuple2 
      # Example
  
      cdef int i, nTuple1, nTuple2
  
      nTuple1 = len(Tuple1)    
      for i in range(nTuple1):
          Tuple1[i] = Tuple1[i]**2
  
      nTuple2 = len(Tuple2)
      for i in range(nTuple2):
          Tuple2[i] = Tuple2[i]/2
  
      return Tuple1, Tuple2
  </code></pre>