Caffe
Public Member Functions | Protected Member Functions | List of all members
caffe::SigmoidLayer< Dtype > Class Template Reference

Sigmoid function non-linearity $ y = (1 + \exp(-x))^{-1} $, a classic choice in neural networks. More...

#include <sigmoid_layer.hpp>

Inheritance diagram for caffe::SigmoidLayer< Dtype >:
caffe::NeuronLayer< Dtype > caffe::Layer< Dtype >

Public Member Functions

 SigmoidLayer (const LayerParameter &param)
 
virtual const char * type () const
 Returns the layer type.
 
- Public Member Functions inherited from caffe::NeuronLayer< Dtype >
 NeuronLayer (const LayerParameter &param)
 
virtual void Reshape (const vector< Blob< Dtype > *> &bottom, const vector< Blob< Dtype > *> &top)
 Adjust the shapes of top blobs and internal buffers to accommodate the shapes of the bottom blobs. More...
 
virtual int ExactNumBottomBlobs () const
 Returns the exact number of bottom blobs required by the layer, or -1 if no exact number is required. More...
 
virtual int ExactNumTopBlobs () const
 Returns the exact number of top blobs required by the layer, or -1 if no exact number is required. More...
 
- Public Member Functions inherited from caffe::Layer< Dtype >
 Layer (const LayerParameter &param)
 
void SetUp (const vector< Blob< Dtype > *> &bottom, const vector< Blob< Dtype > *> &top)
 Implements common layer setup functionality. More...
 
virtual void LayerSetUp (const vector< Blob< Dtype > *> &bottom, const vector< Blob< Dtype > *> &top)
 Does layer-specific setup: your layer should implement this function as well as Reshape. More...
 
Dtype Forward (const vector< Blob< Dtype > *> &bottom, const vector< Blob< Dtype > *> &top)
 Given the bottom blobs, compute the top blobs and the loss. More...
 
void Backward (const vector< Blob< Dtype > *> &top, const vector< bool > &propagate_down, const vector< Blob< Dtype > *> &bottom)
 Given the top blob error gradients, compute the bottom blob error gradients. More...
 
vector< shared_ptr< Blob< Dtype > > > & blobs ()
 Returns the vector of learnable parameter blobs.
 
const LayerParameter & layer_param () const
 Returns the layer parameter.
 
virtual void ToProto (LayerParameter *param, bool write_diff=false)
 Writes the layer parameter to a protocol buffer.
 
Dtype loss (const int top_index) const
 Returns the scalar loss associated with a top blob at a given index.
 
void set_loss (const int top_index, const Dtype value)
 Sets the loss associated with a top blob at a given index.
 
virtual int MinBottomBlobs () const
 Returns the minimum number of bottom blobs required by the layer, or -1 if no minimum number is required. More...
 
virtual int MaxBottomBlobs () const
 Returns the maximum number of bottom blobs required by the layer, or -1 if no maximum number is required. More...
 
virtual int MinTopBlobs () const
 Returns the minimum number of top blobs required by the layer, or -1 if no minimum number is required. More...
 
virtual int MaxTopBlobs () const
 Returns the maximum number of top blobs required by the layer, or -1 if no maximum number is required. More...
 
virtual bool EqualNumBottomTopBlobs () const
 Returns true if the layer requires an equal number of bottom and top blobs. More...
 
virtual bool AutoTopBlobs () const
 Return whether "anonymous" top blobs are created automatically by the layer. More...
 
virtual bool AllowForceBackward (const int bottom_index) const
 Return whether to allow force_backward for a given bottom blob index. More...
 
bool param_propagate_down (const int param_id)
 Specifies whether the layer should compute gradients w.r.t. a parameter at a particular index given by param_id. More...
 
void set_param_propagate_down (const int param_id, const bool value)
 Sets whether the layer should compute gradients w.r.t. a parameter at a particular index given by param_id.
 

Protected Member Functions

virtual void Forward_cpu (const vector< Blob< Dtype > *> &bottom, const vector< Blob< Dtype > *> &top)
 
virtual void Forward_gpu (const vector< Blob< Dtype > *> &bottom, const vector< Blob< Dtype > *> &top)
 Using the GPU device, compute the layer output. Fall back to Forward_cpu() if unavailable.
 
virtual void Backward_cpu (const vector< Blob< Dtype > *> &top, const vector< bool > &propagate_down, const vector< Blob< Dtype > *> &bottom)
 Computes the error gradient w.r.t. the sigmoid inputs. More...
 
virtual void Backward_gpu (const vector< Blob< Dtype > *> &top, const vector< bool > &propagate_down, const vector< Blob< Dtype > *> &bottom)
 Using the GPU device, compute the gradients for any parameters and for the bottom blobs if propagate_down is true. Fall back to Backward_cpu() if unavailable.
 
- Protected Member Functions inherited from caffe::Layer< Dtype >
virtual void CheckBlobCounts (const vector< Blob< Dtype > *> &bottom, const vector< Blob< Dtype > *> &top)
 
void SetLossWeights (const vector< Blob< Dtype > *> &top)
 

Additional Inherited Members

- Protected Attributes inherited from caffe::Layer< Dtype >
LayerParameter layer_param_
 
Phase phase_
 
vector< shared_ptr< Blob< Dtype > > > blobs_
 
vector< bool > param_propagate_down_
 
vector< Dtype > loss_
 

Detailed Description

template<typename Dtype>
class caffe::SigmoidLayer< Dtype >

Sigmoid function non-linearity $ y = (1 + \exp(-x))^{-1} $, a classic choice in neural networks.

Note that the gradient vanishes as the values move away from 0. The ReLULayer is often a better choice for this reason.

Member Function Documentation

◆ Backward_cpu()

template<typename Dtype >
void caffe::SigmoidLayer< Dtype >::Backward_cpu ( const vector< Blob< Dtype > *> &  top,
const vector< bool > &  propagate_down,
const vector< Blob< Dtype > *> &  bottom 
)
protectedvirtual

Computes the error gradient w.r.t. the sigmoid inputs.

Parameters
topoutput Blob vector (length 1), providing the error gradient with respect to the outputs
  1. $ (N \times C \times H \times W) $ containing error gradients $ \frac{\partial E}{\partial y} $ with respect to computed outputs $ y $
propagate_downsee Layer::Backward.
bottominput Blob vector (length 1)
  1. $ (N \times C \times H \times W) $ the inputs $ x $; Backward fills their diff with gradients $ \frac{\partial E}{\partial x} = \frac{\partial E}{\partial y} y (1 - y) $ if propagate_down[0]

Implements caffe::Layer< Dtype >.

◆ Forward_cpu()

template<typename Dtype >
void caffe::SigmoidLayer< Dtype >::Forward_cpu ( const vector< Blob< Dtype > *> &  bottom,
const vector< Blob< Dtype > *> &  top 
)
protectedvirtual
Parameters
bottominput Blob vector (length 1)
  1. $ (N \times C \times H \times W) $ the inputs $ x $
topoutput Blob vector (length 1)
  1. $ (N \times C \times H \times W) $ the computed outputs $ y = (1 + \exp(-x))^{-1} $

Implements caffe::Layer< Dtype >.


The documentation for this class was generated from the following files: