[MXNET-1408] Adding test to verify Large Tensor Support for ravel and…

… unravel

tests/nightly/test_large_array.py

@@ -279,6 +279,19 @@ def test_diag():
     assert_almost_equal(r.asnumpy(), np.diag(a_np, k=k))
 
 
+def test_ravel_and_unravel():
+    idxs_2d = [[LARGE_X-1,LARGE_X-100,6],[SMALL_Y-1,SMALL_Y-10,1]]
+    idx = mx.nd.array(1)
+    def test_ravel_multi_index():
+        idx = mx.nd.ravel_multi_index(mx.nd.array(idxs_2d, dtype=np.int64), shape=(LARGE_X,SMALL_Y))
+        idx_numpy = np.ravel_multi_index(idxs_2d, (LARGE_X,SMALL_Y))
+        assert np.sum(1 for i in range(idx.size) if idx[i] == idx_numpy[i]) == 3
+
+    def test_unravel_index():
+        original_2d_idxs = mx.nd.unravel_index(mx.nd.array(idx, dtype=np.int64), shape=(LARGE_X,SMALL_Y))
+        assert (original_2d_idxs.asnumpy() == np.array(idxs_2d)).all()
+
+
 if __name__ == '__main__':
     import nose
     nose.runmodule()