@Override
public INDArray backprop(INDArray output, int miniBatchSize) {
if (output == null)
return null; // In a few cases: output may be null, and this is valid. Like time series data
// -> embedding layer
// Need to reshape FeedForward layer epsilons (2d) to 3d (for use in RNN layer backprop
// calculations)
if (output.rank() != 2)
throw new IllegalArgumentException(
"Invalid input: expect NDArray with rank 2 (i.e., epsilons from feed forward layer)");
if (output.ordering() == 'c') output = Shape.toOffsetZeroCopy(output, 'f');
int[] shape = output.shape();
INDArray reshaped = output.reshape('f', miniBatchSize, shape[0] / miniBatchSize, shape[1]);
return reshaped.permute(0, 2, 1);
}
