private double GetSquaredError(double[] expectedOutput)
{
double error = 0.0;
Layer lastLayer = this.net[net.LayersCount - 1];
double[] currError = errors[net.LayersCount - 1];
int limit = net[net.LayersCount - 1].Size;
IActivationFunction func = net[0][0].ActivationFunction;
for (int i = 0; i < limit; i++)
{
double err = expectedOutput[i] - lastLayer[i].Output;
currError[i] = err * func.DerivativeFromY(lastLayer[i].Output);
error += err * err;
}
for (int i = net.LayersCount - 2; i >= 0; i--)
{
lastLayer = net[i];
currError = errors[i];
Layer nextLayer = net[i + 1];
double[] nextError = errors[i + 1];
for (int j = 0; j < lastLayer.Size; j++)
{
double sum = 0.0;
for (int k = 0; k < nextLayer.Size; k++)
{
sum += nextError[k] * nextLayer[k].Weights[j];
}
currError[j] = sum * func.DerivativeFromY(lastLayer[j].Output);
}
}
return(error);
}