private double[] GetLayerError(TDerivative PWhichDeriv, int PWhichLayer,
double[] POutput, double[] PNextLayerError)
{
int numneurons = layers[PWhichLayer].NumNeurons;
int numneuronsnextlayer = layers[PWhichLayer + 1].NumNeurons;
double[][] layerweights = weights[PWhichLayer + 1];
double[] error = new double[numneurons];
for (int i = 0; i < numneurons; i++)
{
error[i] = 0;
for (int j = 0; j < numneuronsnextlayer; j++)
{
double curweight = layerweights[j][i];
double addtoerror = PNextLayerError[j] * curweight;
if (PWhichDeriv != TDerivative.First)
{
addtoerror *= curweight;
}
error[i] += addtoerror;
}
double deriv = layers[PWhichLayer].FirstDerivative(POutput[i]);
error[i] *= deriv;
if (PWhichDeriv != TDerivative.First)
{
error[i] *= deriv;
}
}
return(error);
}
private double[][][] GetDerivativesFromOutputBatch(TDerivative PWhichDeriv, double[][][] POutput,
double[][] PInput, double[][] PDesired)
{
double[][][] derivatives = ArrayInitOnePerWeight();
Utility.ZeroArray(derivatives);
int numcases = POutput.GetLength(0);
for (int i = 0; i < numcases; i++)
{
Utility.AddArrays(derivatives, GetDerivativesFromOutput(PWhichDeriv, POutput[i], PInput[i], PDesired[i]));
}
Utility.ScaleArray(derivatives, 1 / ((double)numcases));
return(derivatives);
}
private double[] LastLayerError(TDerivative PWhichDeriv, double[] POutput,
double[] PDesired)
{
int numneurons = layers[numlayers - 1].NumNeurons;
double[] error = new double[numneurons];
for (int i = 0; i < numneurons; i++)
{
if (PWhichDeriv == TDerivative.First)
{
error[i] = POutput[i] - PDesired[i];
}
else
{
error[i] = 1;
}
}
return(error);
}
private void CalculateDerivativesFromError(TDerivative PWhichDeriv, int PWhichLayer,
double[][] PDerivatives, double[] PLayerError, double[] PPreviousOutputs)
{
int numneurons = layers[PWhichLayer].NumNeurons;
int numneuronspreviouslayer = weights[PWhichLayer][0].GetLength(0);
for (int i = 0; i < numneurons; i++)
{
for (int j = 0; j < numneuronspreviouslayer; j++)
{
PDerivatives[i][j] = PLayerError[i] * PPreviousOutputs[j];
if (PWhichDeriv != TDerivative.First)
{
PDerivatives[i][j] *= PPreviousOutputs[j];
}
}
PDerivatives[i][numneuronspreviouslayer] = PLayerError[i];
}
}
private double[][][] GetDerivativesFromOutput(TDerivative PWhichDeriv, double[][] POutput,
double[] PInput, double[] PDesired)
{
double[][][] derivatives = ArrayInitOnePerWeight();
double[] layererror = LastLayerError(PWhichDeriv, POutput[numlayers - 1], PDesired);
double[] previousoutput = PInput;
if (numlayers > 1)
{
previousoutput = POutput[numlayers - 2];
}
CalculateDerivativesFromError(PWhichDeriv, numlayers - 1, derivatives[numlayers - 1], layererror, previousoutput);
for (int i = numlayers - 2; i >= 0; i--)
{
layererror = GetLayerError(PWhichDeriv, i, POutput[i], layererror);
previousoutput = PInput;
if (i != 0)
{
previousoutput = POutput[i - 1];
}
CalculateDerivativesFromError(PWhichDeriv, i, derivatives[i], layererror, previousoutput);
}
return(derivatives);
}
