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反向传播算法C语言实现

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反向传播算法C语言实现

//实现对异或的分类
#include 
#include 
#include 
#include 
#define PN 4
#define INPUT 2
#define HIDDEN 2
#define TARGET 1
#define OUTPUT 1
struct NN
{
  int ni;
  int nh;
  int no;
  double * ai;
  double * ah;
  double * ao;
  double * wi;
  double * wo;
  double * ci;
  double * co;
};
double rand(double a, double b) //就是这个随机数函数,不知道是不是哪里有错
{
  srand(time(NULL));
  double tmp = rand() / (double)(RAND_MAX);
  return (b - a) * tmp + a;
}
double * makeMatrix(int i, int j, double fill)
{
  double * matrix = (double *) malloc (i * j * sizeof(double));
  int m, n;
  for (m = 0;m < i;++ m) {
    for (n = 0;n < j;++ n) { *(matrix + m * j + n) = fill; } } return matrix; } double sigmoid(double x) { return (exp(x) - exp(-x)) / (exp(x) + exp(-x)); } double dsigmoid(double x) { return 1.0 - x * x; } void init(NN * self, int ni, int nh, int no) { int i, j; self->ni = ni + 1;
  self->nh = nh;
  self->no = no;
  self->ai = (double *) malloc (sizeof(double) * self->ni);
  self->ah = (double *) malloc (sizeof(double) * self->nh);
  self->ao = (double *) malloc (sizeof(double) * self->no);
  for (i = 0;i < self->ni;++ i) {
    self->ai[i] = 1.0;
  }
  for (i = 0;i < self->nh;++ i) {
    self->ah[i] = 1.0;
  }
  for (i = 0;i < self->no;++ i) {
    self->ao[i] = 1.0;
  }
  self->wi = makeMatrix(self->ni, self->nh, 0);
  self->wo = makeMatrix(self->nh, self->no, 0);

  self->wi[0] = 0.13776874061001926;
  self->wi[1] = 0.10318176117612099;
  self->wi[2] = -0.031771367667662004;
  self->wi[3] = -0.09643329988281467;
  self->wi[4] = 0.004509888547443414;
  self->wi[5] = -0.03802634501983429;
  self->wo[0] = 1.1351943561390905;
  self->wo[1] = -0.7867490956842902;//以上的随机数是我用python生成的,不知为何C生成的随机数不能达到要求

  self->ci = makeMatrix(self->ni, self->nh, 0);
  self->co = makeMatrix(self->nh, self->no, 0);
}
double * update(NN * self, double *inputs)
{
  if (INPUT != self->ni - 1) {
    printf("wrong number of inputs\n");
  }

  int i, j, k;
  for (i = 0;i < self->ni - 1;++ i) {
    self->ai[i] = inputs[i];
  }
  for (j = 0;j < self->nh;++ j) {
    double sum = 0;
    for (i = 0;i < self->ni;++ i) {
      sum += self->ai[i] * self->wi[i * self->nh + j];
    }
    self->ah[j] = sigmoid(sum);
  }
  for (k = 0;k < self->no;++ k) {
    double sum = 0;
    for (j = 0;j < self->nh;++ j) {
      sum += self->ah[j] * self->wo[j * self->no + k];
    }
    self->ao[k] = sigmoid(sum);
  }
  double *output = (double *) malloc (sizeof(double) * self->no);
  for (i = 0;i < self->no;++ i) {
    *(output + i) = self->ao[i];
  }
  return output;
}
double backprobagation(NN * self, double *targets, double N, double M)
{
  if (TARGET != self->no) {
    printf("wrong number of target values\n");
  }

  int i, j, k;
  double *output_deltas = (double *) calloc (self->no, sizeof(double));
  for (k  = 0;k < self->no;++ k) {
    double error = targets[k] - self->ao[k];
    output_deltas[k] = dsigmoid(self->ao[k]) * error;
  }

  double *hidden_deltas = (double *) calloc (self->nh, sizeof(double));
  for (j = 0;j < self->nh;++ j) {
    double error = 0;
    for (k = 0;k < self->no;++ k) {
      error += output_deltas[k] * self->wo[j * self->no + k];
    }
    hidden_deltas[j] = dsigmoid(self->ah[j]) * error;
  }

  for (j = 0;j < self->nh;++ j) {
    for (k = 0;k < self->no;++ k) {
      double change = output_deltas[k] * self->ah[j];
      self->wo[j * self->no + k] += (N * change + M * self->co[j * self->no + k]);
      self->co[j * self->no + k] = change;
    }
  }
  for (i = 0;i < self->ni;++ i) {
    for (j = 0;j < self->nh;++ j) {
      double change = hidden_deltas[j] * self->ai[i];
      self->wi[i * self->nh + j] += (N * change + M * self->ci[i * self->nh + j]);
      self->ci[i * self->nh + j] = change;
    }
  }
  double error = 0;
  for (k = 0;k < TARGET;++ k) { error += 0.5 * (targets[k] - self->ao[k]) * (targets[k] - self->ao[k]);
  }
  return error;
}
void test(NN * self, double *inputs, double *targets)
{
  int i, j, k;
  for (i = 0;i <  PN;++ i) {
    double * input = (double *) malloc (sizeof(double) * INPUT);
    for (j = 0;j < INPUT;++ j) {
      input[j] = inputs[i * INPUT + j];
      printf("%lf ", input[j]);
    }
    update(self, input);
    for (k = 0;k < self->no;++ k) {
      printf("%lf ", self->ao[k]);
    }
    printf("\n");
  }
}
void train(NN * self, double *inputs, double *targets, int iteration, double N, double M)
{
  int i, j, k, p;
  for (i = 0;i < iteration;++ i) {
    double error = 0;
    for (p = 0;p < PN;++ p) {
      double *input = (double *) malloc (sizeof(double) * INPUT);
      double *target = (double *) malloc (sizeof(double) * TARGET);
      for (j = 0;j < INPUT;++ j) {
*(input + j) = inputs[p * INPUT + j];
      }
      for (k = 0;k < TARGET;++ k) {
*(target + k) = targets[p * TARGET + k];
      }
      update(self, input);
      error += backprobagation(self, target, N, M);
    }
    if (i % 100 == 0) {
      printf("error %-.5lf\n", error);
    }
  }
}
int main()
{
  double inputs[PN * INPUT] = {0, 0, 0, 1, 1, 0, 1, 1};
  double targets[PN * TARGET] = {0, 1, 1, 0};
  NN * self = (NN *) calloc (1, sizeof(NN));
  init(self, 2, 2, 1);
  train(self, inputs, targets, 1000, 0.5, 0.1);
  test(self, inputs, targets);
  return 0;
}

 


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