Metode Iterasi

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

double N,a,e,xr,x0,yr;
int i;

double f(double x){
    return exp(-x) - x;
}

double g(double x){
    return exp(-x);
}

void title(){
    puts("Praktikum Metode Numerik");
    puts("Metode Iterasi Sederhana\n");
}

void input(){
    fflush(stdin);
    printf("Pendekatan awal : ");
    scanf("%lf",&a);
    fflush(stdin);
    printf("Masukkan toleransi : ");
    scanf("%lf",&e);

    fflush(stdin);
    printf("Masukkan jumlah iterasi : ");
    scanf("%lf",&N);
}

//Metode Iterasi Sederhana
void metode(){

    xr = a;
    i = 0;
    printf("%-4s \t%-8s \t%-8s \t%-8s\n","i","xr","f(xr)","g(xr)");
    printf("%-4d \t%-8lg \t%-8lg \t%-8lg\n",i+1,xr,f(xr),g(xr));
    do{
        i++;
        xr = g(xr);
        yr = f(xr);
        printf("%-4d \t%-8lg \t%-8lg \t%-8lg\n",i+1,xr,f(xr),g(xr));
    }while(fabs(f(xr))>e && i<N);

    printf("Nilai xr = %lg\ndan f(xr) = %lg\n\n",xr,f(xr));
    printf("Nilai error nya : %lg\n",fabs(f(xr)));
}

char ulangi(){
    char opt;
    fflush(stdin);
    printf("Ulangi [y/t] ? :");
    scanf("%c",&opt);
    if(opt=='y'||opt=='Y')
        opt=1;
    else
        opt=0;
    return opt;
}

int main()
{
    title();
    do{
        input();
        metode();
    }while(ulangi());
    return 0;
}