You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: AffineGridGenerator_fix.m
    path of file: ./repos/Pedestrian_Alignment/matlab/+dagnn
    
    the code of the file until where you have to start completion: classdef AffineGridGenerator_fix < dagnn.Layer
%DAGNN.AFFINEGRIDGENERATIOR  Generate an affine grid for bilinear resampling
%   This layer maps 1 x 1 x 6 x N affine transforms to 2 x Ho x Wo x N
%   sampling grids compatible with dagnn.B
    
function [derInputs, derParams] = backward(obj, inputs, ~, derOutputs)

      useGPU = isa(derOutputs{1}, 'gpuArray');
      dY = derOutputs{1};
      nbatch = size(dY,4);

      % cudnn compatibility:
      dY = permute(dY, [3,2,1,4]);

      % create the gradient buffer:
      dA = zeros([2,1,nbatch], 'single');
      if useGPU, dA = gpuArray(dA); end