//---------------------------------------------------------------------------

#include <vcl.h>
#pragma hdrstop

//---------------------------------------------------------------------------

#pragma argsused
#include<iostream.h>
#include<conio.h>
#include<math.h>


int iter, funct;
double m_x;

double func_y(double x)
{
    return pow(M_E,x)-(x*x*x)/3+2*x;
}

double general_search(double a, double b, double e)
{
    iter=0;
    funct=0;
    int n=2/e+1;
    double h=fabs(a-b)/n;
    iter++;

    double m_y, temp_x, temp_y;



    m_x=a;
    m_y=func_y(m_x);
    funct++;
    temp_x=m_x;

    while(temp_x<b)
    {
        temp_x+=h;
        temp_y=func_y(temp_x);
        funct++;

        if(temp_y<m_y)
        {
            m_y=temp_y;
            m_x=temp_x;
        }
    }
    return m_y;
}


double interval_bisection(double a,double b,double e)
{
    iter=0;
    funct=0;

    double x1, x2, x3, x4, x5;
    double y1, y2, y3, y4, y5;
    double m_y;


    x1 = a; x5 = b;

    x3 = x1 + (x5 - x1)/2.0;
    y3 = func_y(x3);
    funct++;

    while (fabs(x5 - x1) > e)
    {
        iter++;


        x2 = x1 + (x3 - x1)/2.0;
        x4 = x5 - (x5 - x3)/2.0;

        y2 = func_y(x2);
        y4 = func_y(x4);
        funct += 2;


        if (y2<y3)
        {
            x5 = x3;
            y5 = y3;
            x3=x2;
            y3=y2;
            m_x = x2;
            m_y = y2;
            continue;
        }

        if (y4<y3)
        {
            x1 = x3;
            y1 = y3;
            x3=x4;
            y3=y4;
            m_x = x4;
            m_y = y4;
            continue;
        }

        else
        {
            x1 = x2;
            y1 = y2;
            x5=x4;
            y5=y4;
            m_x = x3;
            m_y = y3;
            continue;
        }

    }

    return m_y;
}

double gold_section(double a, double b, double e)
{
    double f = (sqrt(5) + 1)/2;
    double x1 = a, x4 = b, x2, x3;
    double y1 =func_y(x1), y4 = func_y(x4), y2, y3;
    double gold, m_y;

    funct = 2;
    iter = 0;

    gold = (x4 - x1)/f;
    x2 = x4 - gold;
    x3 = x1 + gold;

    y2 = func_y(x2);
    y3 = func_y(x3);
    funct+=2;

    while (fabs(x4 - x1) > e)
    {
        iter++;


        if (y2 < y3)
        {
            m_x = x2; m_y = y2;
            x4 = x3; y4 = y3;
            x3 = x2; y3 = y2;
            gold =(x4 - x1)/f;
            x2 = x4 - gold;
            y2 = func_y(x2);
            funct++;
            continue;
        }

        if (y3 < y2)
        {
            m_x = x3; m_y = y3;
            x1 = x2; y1 = y2;
            x2 = x3; y2 = y3;
            gold =(x4 - x1)/f;
            x3 = x1 + gold;
            y3 = func_y(x3);
            funct++;
            continue;
        }
    }

    return m_y;
}


void main()
{
    cout.precision(10);
    cout<<"General search:\n\nf(x*)="<<general_search(-2,0,0.00001)<<endl;
    cout<<"x*="<<m_x<<endl;
    cout<<"Function usage counter: "<<funct<<endl;
    cout<<"Iteration counter: "<<iter<<endl;

    cout<<"\nInterval Bisection:\n\nf(x*)="<<interval_bisection(-2,0,0.00001)<<endl;
    cout<<"x*="<<m_x<<endl;
    cout<<"Function usage counter: "<<funct<<endl;
    cout<<"Iteration counter: "<<iter<<endl;

    cout<<"\nGold Section:\n\nf(x*)="<<gold_section(-2,0,0.00001)<<endl;
    cout<<"x*="<<m_x<<endl;
    cout<<"Function usage counter: "<<funct<<endl;
    cout<<"Iteration counter: "<<iter<<endl;
    getch();
}
//---------------------------------------------------------------------------