text: #include "activation_layer.h"
  #include "utils.h"
  #include "cuda.h"
  #include "blas.h"
  #include "gemm.h"
  
  #include <math.h>
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  
  layer make_activation_layer(int batch, int inputs, ACTIVATION activation)
  {
    layer l = { 0 };
    l.type = ACTIVE;
  
    l.inputs = inputs;
    l.outputs = inputs;
    l.batch = batch;
  
    l.output = calloc(batch * inputs, sizeof(float*));
    l.delta = calloc(batch * inputs, sizeof(float*));
  
    l.forward = forward_activation_layer;
    l.backward = backward_activation_layer;
  #ifdef GPU
    l.forward_gpu = forward_activation_layer_gpu;
    l.backward_gpu = backward_activation_layer_gpu;
  
    l.output_gpu = cuda_make_array(l.output, inputs * batch);
    l.delta_gpu = cuda_make_array(l.delta, inputs * batch);
  #endif
    l.activation = activation;
    fprintf(stderr, "Activation Layer: %d inputs\n", inputs);
    return l;
  }
  
  void forward_activation_layer(layer l, network net)
  {
    copy_cpu(l.outputs * l.batch, net.input, 1, l.output, 1);
    activate_array(l.output, l.outputs * l.batch, l.activation);
  }
  
  void backward_activation_layer(layer l, network net)
  {
    gradient_array(l.output, l.outputs * l.batch, l.activation, l.delta);
    copy_cpu(l.outputs * l.batch, l.delta, 1, net.delta, 1);
  }
  
  #ifdef GPU
  
  void forward_activation_layer_gpu(layer l, network net)
  {
    copy_gpu(l.outputs * l.batch, net.input_gpu, 1, l.output_gpu, 1);
    activate_array_gpu(l.output_gpu, l.outputs * l.batch, l.activation);
  }
  
  void backward_activation_layer_gpu(layer l, network net)
  {
    gradient_array_gpu(l.output_gpu, l.outputs * l.batch, l.activation, l.delta_gpu);
    copy_gpu(l.outputs * l.batch, l.delta_gpu, 1, net.delta_gpu, 1);
  }
  #endif
  