momentum_op.cc

/* Copyright (c) 2016 PaddlePaddle Authors. All Rights Reserve.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License. */

#include "paddle/operators/momentum_op.h"

namespace paddle {
namespace operators {

class MomentumOp : public framework::OperatorWithKernel {
 public:
  using framework::OperatorWithKernel::OperatorWithKernel;

 protected:
  void InferShape(framework::InferShapeContextBase *ctx) const override {
    PADDLE_ENFORCE(ctx->HasInput("Param"),
                   "Input(param) of Momentum should not be null.");
    PADDLE_ENFORCE(ctx->HasInput("Grad"),
                   "Input(grad) of Momentum should not be null.");
    PADDLE_ENFORCE(ctx->HasInput("Velocity"),
                   "Input(velocity) of Momentum should not be null.");
    PADDLE_ENFORCE(ctx->HasInput("LearningRate"),
                   "Input(LearningRate) of Momentum should not be null.");

    PADDLE_ENFORCE(ctx->HasOutput("ParamOut"),
                   "Output(ParamOut) of Momentum should not be null.");
    PADDLE_ENFORCE(ctx->HasOutput("VelocityOut"),
                   "Output(VelocityOut) of Momentum should not be null.");

    auto param_dim = ctx->GetInputDim("Param");
    PADDLE_ENFORCE_EQ(
        param_dim, ctx->GetInputDim("Grad"),
        "Param and Grad input of MomentumOp should have the same dimension.");
    PADDLE_ENFORCE_EQ(
        param_dim, ctx->GetInputDim("Velocity"),
        "Param and Velocity of MomentumOp should have the same dimension.");
    PADDLE_ENFORCE_EQ(framework::product(ctx->GetInputDim("LearningRate")), 1,
                      "Learning_rate should be a scalar");

    ctx->SetOutputDim("ParamOut", param_dim);
    ctx->SetOutputDim("VelocityOut", param_dim);
  }
};

class MomentumOpMaker : public framework::OpProtoAndCheckerMaker {
 public:
  MomentumOpMaker(framework::OpProto *proto,
                  framework::OpAttrChecker *op_checker)
      : OpProtoAndCheckerMaker(proto, op_checker) {
    AddInput("Param", "Input parameter");
    AddInput("Grad", "Input gradient");
    AddInput("Velocity", "Input velocity");
    AddInput("LearningRate", "Input learning rate");

    AddOutput("ParamOut", "Output parameter");
    AddOutput("VelocityOut", "Output velocity");

    AddAttr<float>("mu", "Momentum coefficient");
    AddComment(R"DOC(

Momentum Algorithm (momentum).

velocity_out = mu * velocity - learning_rate * grad
param_out = param + velocity_out

Ref: Sutskever, Ilya, et al. "On the importance of initialization
     and momentum in deep learning." ICML 2013;
     http://jmlr.org/proceedings/papers/v28/sutskever13.pdf

)DOC");
  }
};
}  // namespace operators
}  // namespace paddle

namespace ops = paddle::operators;
REGISTER_OP_WITHOUT_GRADIENT(momentum, ops::MomentumOp, ops::MomentumOpMaker);
REGISTER_OP_CPU_KERNEL(
    momentum, ops::MomentumOpKernel<paddle::platform::CPUPlace, float>);