Merge pull request #5144 from nouiz/float16_var

theano/tensor/basic.py

@@ -3249,11 +3249,12 @@ def var(input, axis=None, ddof=0, keepdims=False, corrected=False):
     centered_input = input - mean_input
 
     # return the mean sqr
+    two = constant(2, dtype=centered_input.dtype)
     if ddof == 0:
-        v = mean((centered_input ** 2), axis, keepdims=keepdims)
+        v = mean((centered_input ** two), axis, keepdims=keepdims)
     else:
         shp = shape(input) - ddof
-        v = sum((centered_input ** 2), axis=axis, keepdims=keepdims)
+        v = sum((centered_input ** two), axis=axis, keepdims=keepdims)
         for i in axis:
             v = true_div(v, shp[i])
 

theano/tensor/tests/test_basic.py

@@ -6400,6 +6400,9 @@ def test_var():
     v = v - error
     assert numpy.allclose(v, f(a_val))
 
+    # Test that we don't upcast float16 computation
+    assert theano.tensor.vector(dtype='float16').var().dtype == 'float16'
+
 
 class T_sum(unittest.TestCase):
     def test_sum_overflow(self):