Newton_raphson.c

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#define f(x) ((x*x*x)-18)
#define fd(x) (3*x*x)      //derivative of f(x)
#define fdd(x) 6*x         //second derivative of f(x)
int main(){
float x0,x1,error,error-old,converge,order;
int i=0;
printf("Input the approximation : ");
scanf("%f",&x0);
converge= (f(x0)*fdd(x0))/(fd(x0)*fd(x0));
if(converge >1)
        exit(1);
printf("Ite\tX0\t\tX1\t\tError\t\tOrder\n");
do{
        errorold=error;
        x1=x0-(f(x0)/fd(x0));                   //formula for the next point 
        if(f(x1)==0){
                break;
        }
        error=fabs(x1-x0);
        printf("%2d\t%4.6f\t%4.6f\t%4.6f\t",++i,x0,x1,error);
        if(i==1||error==0||errorold==1){
                printf("-----\n");
        }
        else {order=log(error)/log(errorold);
        printf("%4.6f\n",order);
        }
        x0=x1;
}while(error>0.00005);
printf("Root is %4.6f",x0);
return 0;
}