One more test + some doc

doc/library/tensor/basic.txt

@@ -1643,6 +1643,16 @@ Linear Algebra
     :note: See :func:`tensordot` and :func:`batched_dot` for
         supplementary documentation.
 
+.. class:: _nd_grid(object)
+
+    Create a dense n-dimensional 'meshgrid' with equally spaced points.
+    Used to create the instance ''mgrid'' and ''ogrid'' which act similarly
+    to their numpy equivalents.
+    
+    :param sparse: boolean, optional, default=True. Specifying False leads to 
+                   the equivalent of numpy's mgrid functionality. Specifying 
+                   True leads to the equivalent of ogrid.
+
 
 
 Gradient / Differentiation

theano/tensor/basic.py

@@ -4644,7 +4644,7 @@ class _nd_grid(object):
                 raise NotImplementedError("Not implemented for slices "
                                           "whose step is complex")
         ranges = [arange(sl.start or 0,
-                         sl.stop or None,
+                         sl.stop,
                          sl.step or 1) for sl in args[0]]
         shapes = [tuple([1] * j + [r.shape[0]] + [1] * (ndim - 1 - j))
                   for j, r in enumerate(ranges)]

theano/tensor/tests/test_basic.py

@@ -5516,6 +5516,20 @@ class TestNdGrid(unittest.TestCase):
             for ng, tg in zip(n, t):
                 assert_array_equal(ng, tg)
 
+    def test_ogrid_theano_variable_numpy_equiv(self):
+        nfogrid = numpy.ogrid[0:1:.1, 1:10:1., 10:100:10.]
+        niogrid = numpy.ogrid[0:2:1, 1:10:1, 10:100:10]
+        i,j,k = dscalars('i','j','k')
+        l,m,n = iscalars('l','m','n')
+        tfogrid = ogrid[i:1:.1, 1:j:1., 10:100:k]
+        tiogrid = ogrid[l:2:1, 1:m:1, 10:100:n]
+        ff = theano.function([i, j, k], tfogrid)
+        fi = theano.function([l, m, n], tiogrid)
+        for n, t in zip((nfogrid,niogrid), (ff(0, 10, 10.),fi(0, 10, 10))):
+            for ng, tg in zip(n, t):
+                assert_array_equal(ng, tg)
+                
+                
 class TestInversePermutation(unittest.TestCase):
     def setUp(self):
         utt.seed_rng()