/// <summary>
/// Spatials the maximum pooling backward.
/// </summary>
/// <param name="input">The input.</param>
/// <param name="gradOutput">The grad output.</param>
/// <param name="gradInput">The grad input.</param>
/// <param name="indices">The indices.</param>
/// <param name="cd">The cd.</param>
/// <param name="ceilMode">if set to <c>true</c> [ceil mode].</param>
public static void SpatialMaxPoolingBackward(NDArray input, NDArray gradOutput, NDArray gradInput, NDArray indices, ConvolutionDesc2d cd, bool ceilMode)
{
var dimw = 3;
var dimh = 2;
var dimc = 1;
var nbatch = input.Shape[0];
var nslices = input.Shape[dimc];
var iheight = input.Shape[dimh];
var iwidth = input.Shape[dimw];
var owidth = gradOutput.Shape[dimw];
var oheight = gradOutput.Shape[dimh];
Ops.Fill(gradInput, 0);
using (var gradOutputContig = Ops.AsContiguous(gradOutput))
{
for (int i = 0; i < nbatch; ++i)
{
using (var gradInput_i = gradInput.Select(0, i))
using (var gradOutput_i = gradOutputContig.Select(0, i))
using (var indices_i = indices.Select(0, i))
{
IntPtr gradInput_iPtr, gradOutput_iPtr, indices_iPtr;
using (NativeWrapper.BuildTensorRefPtr(gradInput_i, out gradInput_iPtr))
using (NativeWrapper.BuildTensorRefPtr(gradOutput_i, out gradOutput_iPtr))
using (NativeWrapper.BuildTensorRefPtr(indices_i, out indices_iPtr))
{
CpuOpsNative.TS_SpatialMaxPooling_updateGradInput_frame(gradInput_iPtr, gradOutput_iPtr, indices_iPtr,
nslices, iwidth, iheight,
owidth, oheight,
cd.dW, cd.dH);
}
}
}
}
}
