add alias for sgd

Author: algorithm1832

python/paddle/optim/sgd.py

@@ -12,4 +12,31 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from paddle.optimizer.sgd import SGD  # noqa: F401
+from __future__ import annotations
+
+from typing import TYPE_CHECKING
+
+from paddle.optimizer.sgd import SGD as PaddleSGD
+
+if TYPE_CHECKING:
+    from collections.abc import Sequence
+
+    from paddle import Tensor
+    from paddle.optimizer.optimizer import _ParameterConfig
+
+
+class SGD(PaddleSGD):
+    def __init__(
+        self,
+        params: Sequence[Tensor] | Sequence[_ParameterConfig] | None = None,
+        lr: float | Tensor = 1e-3,
+        momentum: float = 0,
+        dampening: float = 0,
+        weight_decay: float | Tensor = 0,
+        nesterov: bool = False,
+    ) -> None:
+        super().__init__(
+            learning_rate=lr,
+            parameters=params,
+            weight_decay=weight_decay,
+        )

test/legacy_test/test_api_compatibility_part1.py

@@ -2396,5 +2396,35 @@ def test_Compatibility(self):
         paddle.set_rng_state(new_state=states)
 
 
+# Test SGD API compatibility
+class TestSGDAPI(unittest.TestCase):
+    def setUp(self):
+        np.random.seed(2025)
+        self.params = [
+            paddle.to_tensor(
+                np.random.randn(3, 4).astype('float32'), stop_gradient=False
+            )
+        ]
+
+    def test_dygraph_Compatibility(self):
+        paddle.disable_static()
+        # 1. positional arguments
+        sgd1 = paddle.optim.SGD(self.params, 0.01, 0, 0, 1e-4)
+        # 2. keyword arguments
+        sgd2 = paddle.optim.SGD(
+            params=self.params, lr=0.01, momentum=0.9, weight_decay=1e-4
+        )
+        # 3. Mixed arguments
+        sgd3 = paddle.optim.SGD(
+            self.params, 0.01, momentum=0.9, weight_decay=1e-4
+        )
+        # Verify all optimizers created successfully
+        self.assertIsNotNone(sgd1)
+        self.assertIsNotNone(sgd2)
+        self.assertIsNotNone(sgd3)
+
+        paddle.enable_static()
+
+
 if __name__ == '__main__':
     unittest.main()