#include "mlisp.h"
#include <iostream>
#include <cmath>
double a=0.;
double b=2.;
double xmin=0.;
double tolerance=0.00001;
double mphi=(3.-sqrt(5))/2.;
double xa;
double xb;
double ya;
double yb;

double fun(double x){
    x=x-105./106.;
    return (x*atan(x)-1./3.);
}

double golden__section__search(double a, double b);
double golden__start(double a,double b);
double _VVV_try(double a,double b,double xa,double ya,double xb,double yb);
double close__enough_Q(double x,double y);



double golden__section__search(double a, double b){
    {

        (a<b)? xmin=golden__start(a,b) : xmin=golden__start(b,a);
    }
    newline();
    return(xmin);
}


double golden__start(double a,double b){
    {
        xa=a+(mphi*(b-a));
        xb=b-(mphi*(b-a));
    }
    return _VVV_try(a,b,xa,fun(xa),xb,fun(xb));
}


double _VVV_try(double a,double b,double xa,double ya,double xb,double yb){
    close__enough_Q(a,b) ? ((a+b) * 0.5) : (
        display("+"),
        (ya < yb) ? (b =xb, xb = xa, yb = ya, xa = a + (mphi * (b-a)), _VVV_try(a,b,xa,fun(xa),xb,yb)) : ( a= xa, xa =xb, ya = yb, xb = (b - mphi*(b-a)), _VVV_try(a,b, xa, ya, xb, fun(xb))
    ));
}


double close__enough_Q(double x,double y){
    return (abs(x-y)<tolerance);
}

int main(){
    xmin=golden__section__search(a,b);
    display("interval=\t[");
    display(a);
    display(" , ");
    display(b);
    display("]\n");
    display("xmin=\t\t");
    display(xmin);
    newline();
    display("f(xmin)=\t");
    display(fun(xmin));
}