/// <summary>
/// Setup the layer.
/// </summary>
/// <param name="colBottom">Specifies the collection of bottom (input) Blobs.</param>
/// <param name="colTop">Specifies the collection of top (output) Blobs.</param>
public override void LayerSetUp(BlobCollection <T> colBottom, BlobCollection <T> colTop)
{
m_log.CHECK(m_param.eltwise_param.coeff.Count == 0 ||
m_param.eltwise_param.coeff.Count == colBottom.Count, "Eltwise layer takes one coefficient per bottom blob.");
m_log.CHECK(!((m_param.eltwise_param.operation == EltwiseParameter.EltwiseOp.PROD || m_param.eltwise_param.operation == EltwiseParameter.EltwiseOp.DIV) &&
m_param.eltwise_param.coeff.Count > 0), "Eltwise layer only takes coefficients for SUM and SUB operations.");
m_op = m_param.eltwise_param.operation;
m_bCoeffBlob = m_param.eltwise_param.coeff_blob;
if (m_bCoeffBlob)
{
m_log.CHECK(m_op == EltwiseParameter.EltwiseOp.SUM || m_op == EltwiseParameter.EltwiseOp.SUB, "coeff_blob option only implemented for the SUM and SUB operation.");
}
int nCoeffSize = m_param.eltwise_param.coeff.Count;
m_log.CHECK(nCoeffSize == 0 || (!m_bCoeffBlob && nCoeffSize == colBottom.Count) ||
(m_bCoeffBlob && nCoeffSize == colBottom.Count - 1), "Eltwise Layer takes one coefficient per bottom blob.");
m_log.CHECK(m_op == EltwiseParameter.EltwiseOp.SUM || m_op == EltwiseParameter.EltwiseOp.SUB ||
layer_param.eltwise_param.coeff.Count == 0, "Eltwise layer only takes coefficients for SUM and SUB operations.");
// Blob-wise coefficients for the elementwise operation.
m_rgdfCoeffs = Utility.Create <double>(colBottom.Count, 1.0);
int nCoeffBlobCount = (m_bCoeffBlob) ? 1 : 0;
for (int i = 0; i < m_param.eltwise_param.coeff.Count - nCoeffBlobCount; i++)
{
m_rgdfCoeffs[i] = m_param.eltwise_param.coeff[i];
}
m_bStableProdGrad = m_param.eltwise_param.stable_prod_grad;
}
public Eltwise(EltwiseParameter.EltwiseOp operation, float[] coeffs, string name = FUNCTION_NAME, string[] inputNames = null, string[] outputNames = null) : base(name, inputNames, outputNames)
{
this._operation = operation;
this._coeffs = coeffs;
MultiInputForward = ForwardCpu;
MultiOutputBackward = BackwardCpu;
}
public Eltwise(EltwiseParameter.EltwiseOp operation, float[] coeffs, string name = FUNCTION_NAME, string[] inputNames = null, string[] outputNames = null) : base(name, inputNames, outputNames)
{
this._operation = operation;
this._coeffs = coeffs;
InitFunc(new StreamingContext());
}
public static NdArray <Real>[] MultiInputForward(NdArray <Real>[] xs, EltwiseParameter.EltwiseOp operation, float[] coeffs, List <int[]> PrevOutputIndex, IFunction <Real> eltwise)
{
Real[] result = new Real[xs[0].Data.Length];
switch (operation)
{
case EltwiseParameter.EltwiseOp.Prod:
Array.Copy(xs[0].Data, result, result.Length);
for (int i = 1; i < xs.Length; i++)
{
for (int j = 0; j < result.Length; j++)
{
result[j] *= xs[i].Data[j];
}
}
break;
case EltwiseParameter.EltwiseOp.Sum:
if (coeffs != null)
{
for (int i = 0; i < xs.Length; i++)
{
for (int j = 0; j < result.Length; j++)
{
result[j] += xs[i].Data[j] * coeffs[i];
}
}
}
else
{
for (int i = 0; i < xs.Length; i++)
{
for (int j = 0; j < result.Length; j++)
{
result[j] += xs[i].Data[j];
}
}
}
break;
case EltwiseParameter.EltwiseOp.Max:
Array.Copy(xs[0].Data, result, result.Length);
int[] outputIndex = new int[result.Length];
for (int i = 1; i < xs.Length; i++)
{
for (int j = 0; j < result.Length; j++)
{
if (result[j] < xs[i].Data[j])
{
outputIndex[j] = i;
result[j] = xs[i].Data[j];
}
}
}
PrevOutputIndex.Add(outputIndex);
break;
}
return(new [] { NdArray.Convert(result, xs[0].Shape, xs[0].BatchCount, eltwise) });
}
public static void MultiOutputBackward(NdArray <Real> y, NdArray <Real>[] xs, EltwiseParameter.EltwiseOp operation, List <int[]> PrevOutputIndex)
{
Real[][] result = new Real[xs.Length][];
for (int i = 0; i < result.Length; i++)
{
result[i] = new Real[xs[i].Data.Length];
}
switch (operation)
{
case EltwiseParameter.EltwiseOp.Prod:
for (int i = 0; i < result.Length; i++)
{
Array.Copy(y.Grad, result[i], y.Grad.Length);
for (int j = 0; j < xs.Length; j++)
{
if (i != j)
{
for (int k = 0; k < result[i].Length; k++)
{
result[i][k] *= xs[j].Data[k];
}
}
}
}
break;
case EltwiseParameter.EltwiseOp.Sum:
for (int i = 0; i < result.Length; i++)
{
Array.Copy(y.Grad, result[i], result[i].Length);
}
break;
case EltwiseParameter.EltwiseOp.Max:
var prevOutputIndex = PrevOutputIndex[PrevOutputIndex.Count - 1];
PrevOutputIndex.RemoveAt(PrevOutputIndex.Count - 1);
for (int i = 0; i < prevOutputIndex.Length; i++)
{
result[prevOutputIndex[i]][i] = y.Grad[i];
}
break;
}
for (int i = 0; i < xs.Length; i++)
{
for (int j = 0; j < xs[i].Grad.Length; j++)
{
xs[i].Grad[j] += result[i][j];
}
}
}
