public override void _Backward(INode fromNode, IGraphData errorSignal, IContext context,
IReadOnlyList <INode> parents)
{
Debug.Assert(_source._children.Contains(fromNode));
_signalTable[fromNode] = errorSignal;
if (_signalTable.All(s => s.Value != null) && parents?.Any() == true)
{
var firstSignal = _signalTable[_source._children.First()];
var otherSignals = _signalTable.Where(s =>
s.Value != firstSignal && s.Value.Columns == firstSignal.Columns &&
s.Value.Rows == firstSignal.Rows).ToList();
if (otherSignals.Any())
{
var matrix = firstSignal.GetMatrix();
foreach (var item in otherSignals)
{
matrix.AddInPlace(item.Value.GetMatrix());
}
firstSignal = firstSignal.ReplaceWith(matrix);
}
foreach (var parent in parents)
{
context.AddBackward(firstSignal, parent, _source);
}
_source._onBackpropagation?.Invoke(_signalTable);
}
}
public override void _Backward(INode fromNode, IGraphData errorSignal, IContext context, IReadOnlyList <INode> parents)
{
var matrix = errorSignal.GetMatrix();
(IMatrix left, IMatrix right) = matrix.SplitAtColumn(matrix.ColumnCount - _reverseSize);
context.AddBackward(errorSignal.ReplaceWith(left), parents[0], _source);
var batch = context.BatchSequence.MiniBatch;
var sequenceIndex = context.BatchSequence.SequenceIndex;
var reversedSequenceIndex = batch.SequenceCount - sequenceIndex - 1;
_source._reverseBackpropagation.Add(reversedSequenceIndex, (parents[1], errorSignal.ReplaceWith(right)));
_source._contextTable.Add(sequenceIndex, context);
if (sequenceIndex == 0)
{
// process in order as we are pushing onto a stack (so will be read in reverse order)
for (var i = 0; i < batch.SequenceCount; i++)
{
var data = _source._reverseBackpropagation[i];
var reverseContext = _source._contextTable[i];
reverseContext.AddBackward(data.Item2, data.Item1, _source);
}
_source._reverseBackpropagation.Clear();
_source._contextTable.Clear();
}
}
/// <summary>
/// Sends a backpropagation signal further up the graph
/// </summary>
/// <param name="errorSignal">The backpropagating error</param>
/// <param name="context">Graph context</param>
/// <param name="parents">Parents of the current node</param>
protected void _SendErrorTo(IGraphData errorSignal, IContext context, IReadOnlyList <INode> parents)
{
if (parents?.Any() == true)
{
foreach (var parent in parents)
{
context.AddBackward(errorSignal, parent, _source);
}
}
}
/// <summary>
/// Called when backpropagating
/// </summary>
/// <param name="fromNode">The node that sent the backpropagation signal</param>
/// <param name="errorSignal">The backpropagating error</param>
/// <param name="context">Graph context</param>
/// <param name="parents">Parents of the current node</param>
public void Backward(INode fromNode, IGraphData errorSignal, IContext context, IReadOnlyList <INode> parents)
{
if (errorSignal == null)
{
if (parents?.Any() == true)
{
foreach (var parent in parents)
{
context.AddBackward(errorSignal, parent, _source);
}
}
}
else
{
_Backward(fromNode, errorSignal, context, parents);
}
}
public void AddBackward(IGraphData errorSignal, INode target, INode source)
{
_context.AddBackward(errorSignal, target, source);
}
