#include <stdio.h>
#include <stdlib.h>
#include <readline/readline.h>
#include <readline/history.h>

double epsilon(double x){
    double a=0,b=x;
    for(;;){
        double y=(a+b)/2;
        double r=x+y;
        if(r==x){
            if(a==y) return a;
            a=y;
        } else {
            if(b==y) return a;
            b=y;
        }
    }
}

int main(){
    for(;;){
        char *ep,*xp=readline("Please enter x: ");
        if(!xp) {
            printf("\nEnd of file detected--exiting!\n");
            exit(0);
        }
        if(*xp==0) continue;
        add_history(xp);
        double x=strtod(xp,&ep);
        if(xp==ep||*ep!=0) {
            printf("Not a number, try again!\n");
            continue;
        }
        if(x==0.0) {
            printf("Zero detected--exiting!\n");
            exit(0);
        }
        printf("The value of %g was entered for x.\n",x);
        double e=epsilon(x);
        printf("The value of epsilon is %g.\n",e);
        printf("The ratio epsilon/x=%g.\n",e/x);
    }
}