protected override IGraphData _Backpropagate(INode fromNode, IGraphData errorSignal,
IContext context, IReadOnlyList <INode> parents)
{
var tensor = errorSignal.GetMatrix().
ReshapeAs4DTensor(_newHeight, _newWidth, _source._filter.ColumnCount);
var padding = _source._padding;
// calculate the weight and bias updates
using (var update = _im2Col.TransposeThisAndMultiply(tensor))
{
var weightUpdate = update.CombineDepthSlices();
var biasUpdate = tensor.ColumnSums();
context.LearningContext.StoreUpdate(_source, weightUpdate,
err => _source.Update(err, context.LearningContext));
context.LearningContext.StoreUpdate(_source, biasUpdate,
bu => _UpdateBias(bu, context.LearningContext));
}
if (_source._shouldBackpropagate)
{
var filters = _source._filter;
var inputDepth = _source._inputDepth;
var filterWidth = _source._filterWidth;
var filterHeight = _source._filterHeight;
var xStride = _source._xStride;
var yStride = _source._yStride;
var outputRows = _inputHeight + padding * 2;
var outputColumns = _inputWidth + padding * 2;
var outputDepth = _inputDepth;
var reverseIm2Col = tensor.ReverseIm2Col(filters, outputRows, outputColumns, outputDepth,
filterWidth, filterHeight, xStride, yStride);
var delta = reverseIm2Col;
if (padding > 0)
{
var delta2 = delta.RemovePadding(padding);
delta.Dispose();
delta = delta2;
}
return(new Tensor4DGraphData(delta.ReshapeAsMatrix(), _inputHeight, _inputWidth,
inputDepth));
}
return(errorSignal);
}
protected override IGraphData _Backpropagate(INode fromNode, IGraphData errorSignal, IContext context, IReadOnlyList <INode> parents)
{
var lap = context.LinearAlgebraProvider;
var tensor = errorSignal.GetMatrix().ConvertTo4DTensor(_newHeight, _newWidth, _source._filter.ColumnCount);
var padding = _source._padding;
// calculate the weight and bias updates
var weightUpdate = _im2Col.TransposeThisAndMultiply(tensor).CombineDepthSlices();
var biasUpdate = tensor.ColumnSums();
context.LearningContext.StoreUpdate(_source, weightUpdate, err => _source.Update(err, context.LearningContext));
context.LearningContext.StoreUpdate(_source, biasUpdate, bu => _UpdateBias(bu, context.LearningContext));
if (_source._shouldBackpropagate)
{
var filters = _source._filter;
var inputDepth = _source._inputDepth;
var filterWidth = _source._filterWidth;
var filterHeight = _source._filterHeight;
var stride = _source._stride;
var filterList = new List <IReadOnlyList <IVector> >();
for (var i = 0; i < filters.ColumnCount; i++)
{
filterList.Add(filters.Column(i).Split(inputDepth).Select(v => v.Rotate(v.Count / filterWidth)).ToList());
}
using (var reverseIm2Col = tensor.ReverseIm2Col(filterList, _inputHeight, _inputWidth, inputDepth, padding, filterWidth, filterHeight, stride)) {
var delta = reverseIm2Col.ConvertTo4DTensor(_inputHeight + padding * 2, _inputWidth + padding * 2);
if (padding > 0)
{
delta = delta.RemovePadding(padding);
}
return(new Tensor4DGraphData(delta.ConvertToMatrix(), _inputHeight, _inputWidth, inputDepth));
}
}
return(errorSignal);
}