#include <stdlib.h>
#include <stdio.h>

#include <cuda.h>
#include <cuda_runtime.h>
#include <helper_cuda.h>

#define A 3.

/******************* sequential version *****************/
void saxpy_seq(int n, float a, float *x, float *y){
     int i;
     for (i=0; i<n; i++)	 
       y[i]= a * x[i] + y[i];
}

/********************** kernel **************************/
__global__
void saxpy(int n, float a, float *x, float *y)
{
  /* TODO : Calcul de l'indice i*/

  /* TODO - computation */

}


void print(char *name, float *tab, int n)
{
   int k;
   printf("First elements of %s: \n",name);
   for (k=0; k<10; k++) printf("%.2f ",tab[k]);
   printf("\n Last elements of %s: \n", name);
   for (k=n-10; k<n; k++) printf("%.2f ",tab[k]);
   printf("\n");
}



/********************** main **************************/
int main(void)
{
  int n= 1<<20;
  float *h_x, *h_y, *d_x, *d_y;
  h_x = (float*)malloc(n*sizeof(float));
  h_y = (float*)malloc(n*sizeof(float));

  /* TODO : allocate d_x and d_y in GPU memory */

  
  /* Initialisation de x et y*/
  for (int i = 0; i < N; i++) {
    x[i] = 1.0f;
    y[i] = 2.0f;
  }

  /* TODO : copy x and y on GPU */ 



  saxpy_seq(n, A, x, y); 

  /* TODO : kernel call */

  
  /* TODO : Copie du résultat dans y*/
  
  float maxError = 0.0f;
  for (int i = 0; i < N; i++)
    {
      if(y[i] != 4.0f)
	printf("not equal %d %f %f\n", i, y[i], x[i]);
      maxError = max(maxError, abs(y[i]-4.0f));
    }
  printf("Max error: %f\n", maxError);




  /* TODO : free GPU memory */

  free(x);
  free(y);
}