cpuDeltaX
==================

.. js:function:: FullyConnectedLayer.cpuDeltaX()

    CPUによるδxの計算

    .. math::

        \delta x_{j} = \displaystyle \sum_i^y \delta z_i \cdot weight_{i,j}

ソース
^^^^^^

.. code-block:: js

            cpuDeltaX(){
    
                // 出力先
                var output_idx = 0;
    
                // バッチ内のデータに対し
                for (var batch_idx = 0; batch_idx < miniBatchSize; batch_idx++) {
    
                    // 入力に対し
                    for (var x_idx = 0; x_idx < this.prevLayer.unitSize; x_idx++) {
    
                        var sum = 0.0;
    
                        // 重みの行とδzの内積
                        for (var k = 0; k < this.weight.nrow; k++) {
                            var weight_idx = k * this.weight.ncol + x_idx;
                            var delta_z_idx = batch_idx * this.unitSize + k;
                            sum += this.deltaZ.dt[delta_z_idx] * this.weight.dt[weight_idx];
                        }
    
                        this.deltaX.dt[output_idx] = sum;
                        output_idx++;
                    }
                }
            }