二分法

#include "stdio.h"
#include "math.h"
#define f(x) (((x+1)*(x-1))*x-1)
#define e 0.005
void main()
{
   float x,a=1,b=1.5, y=f(a);
    int k=0;
   if(y*f(b)>=0)
   {
       printf("\nThe range is error!");
     return;
   }
   else
     do{
         x=(a+b)/2;
         printf("\nx%d=%6.4f",k,x);
         k++;
         if(f(x)==0)
             break;
         if(f(x)*f(a)<0)
             b=x;
         else
            a=x;
     }while(fabs(b-a)>e);
     printf("\nx=%4.2f\n",x);
}