#include<stdio.h>
#include<math.h>

#define NMAX 100

float func(float x);
float funcd(float x);

main()
{
   float x0,dx,eps=1.0e-6;
   int i=0;
   
   printf("initial value =");
   scanf("%f",&x0);
   
   while(fabs(dx)>eps){
      i++;
      dx=-func(x0)/funcd(x0);
      x0=x0+dx;

      if(i>NMAX){
         printf("not convergence");
         break;
      }
      
   }
   printf("Iteration=%d  x=%15.5f\n",i,x0);
   return(0);
}

float func(float x)
{
   float y;
   y=x-3.0*exp(-x);
   return(y);
}

float funcd(float x)
{
   float yd;
   yd=1.0+3.0*exp(-x);
   return(yd);
}