public Vec Backpropagate()
{
if (NextLayer == null)
{
throw new NotSupportedException("Cannot backpropagate errors on output layer");
}
if (PreviousLayer == null)
{
throw new NotSupportedException("Cannot backpropagate errors on input layer");
}
if (NextLayer.Errors == null)
{
throw new InvalidOperationException("Cannot backpropagate when next layer's errors are null");
}
if (ZValues == null)
{
throw new InvalidOperationException("Cannot backpropagate before forward propagation");
}
var primeOfZs = Activator.ActivatePrime(ZValues);
_errors = NextLayer.Weights.TransposeThisAndMultiply(NextLayer.Errors).PointwiseMultiply(primeOfZs);
return(_errors);
}
