protected void BackwardCpu(NdArray y, NdArray x)
{
int ndim = x.Shape.Length;
if (y.Shape.Length != ndim)
{
NdArray.Sum(y, false, Enumerable.Range(0, y.Shape.Length - ndim).ToArray());
}
List <int> axis = new List <int>();
for (int i = 0; i < x.Shape.Length; i++)
{
if (x.Shape[i] == 1)
{
axis.Add(i);
}
}
if (axis.Count > 0)
{
NdArray result = NdArray.Sum(y, true, axis.ToArray());
for (int i = 0; i < x.Grad.Length; i++)
{
x.Grad[i] += result.Grad[i];
}
}
else
{
for (int i = 0; i < x.Grad.Length; i++)
{
x.Grad[i] += y.Grad[i];
}
}
}