fix(mge/functional): support scalar inputs in elemwise functions

GitOrigin-RevId: 7bce561ee1a48bfba744bde2c88939a0a3ffeabd

python_module/megengine/functional/elemwise.py

@@ -11,6 +11,7 @@ import functools
 
 import megengine._internal as mgb
 
+from ..core.graph import _use_default_if_none
 from ..core.tensor import Tensor, wrap_io_tensor
 
 __all__ = [
@@ -45,11 +46,17 @@ __all__ = [
 
 def _elemwise(mode):  # DONT export
     """Decorator helps to wrap megbrain element-wise oprs"""
-
     def elemwise_decorator(func):
         @functools.wraps(func)
         @wrap_io_tensor
         def elemwise_func(*inputs) -> Tensor:
+            if all(isinstance(i, (int,float)) for i in inputs):
+                device, comp_graph = _use_default_if_none(None, None)
+                ret = mgb.opr.elemwise(*inputs,
+                                       mode=mode,
+                                       comp_node=device,
+                                       comp_graph=comp_graph)
+                return ret.inferred_value[0]
             return mgb.opr.elemwise(*inputs, mode=mode)
 
         return elemwise_func

python_module/test/unit/functional/test_elemwise.py

+# -*- coding: utf-8 -*-
+# MegEngine is Licensed under the Apache License, Version 2.0 (the "License")
+#
+# Copyright (c) 2014-2020 Megvii Inc. All rights reserved.
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT ARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+import numpy as np
+
+import megengine.functional as F
+from megengine import tensor
+
+from megengine.test import assertTensorClose
+
+
+def test_abs():
+    assertTensorClose(
+        F.abs(tensor([-3., -4., -5.])).numpy(),
+        np.abs(np.array([-3., -4., -5.], dtype=np.float32)))
+
+    assertTensorClose(F.abs(-3.), np.abs(np.float32(-3.)))
+
+
+def test_multiply():
+    assertTensorClose(F.multiply(-3., -4.),
+                      np.multiply(np.float32(-3.), np.float32(-4.)))
+
+    assertTensorClose(
+        F.multiply(tensor([3., 4.]), 4.).numpy(),
+        np.multiply(np.array([3., 4.], dtype=np.float32), 4.))
+
+    assertTensorClose(
+        F.multiply(4., tensor([3., 4.])).numpy(),
+        np.multiply(4., np.array([3., 4.], dtype=np.float32)))
+
+    assertTensorClose(
+        F.multiply(tensor([3., 4.]), tensor([3., 4.])).numpy(),
+        np.multiply(np.array([3., 4.], dtype=np.float32),
+                    np.array([3., 4.], dtype=np.float32)))