#include <iostream>
#include <math.h>
#include <stdlib.h>

using namespace std;

double e;
double x1;
double k;
double f(double x,int s)
{
    if (s==1)
        return 2.0*x*x+3.0*exp(-x);
    else if (s==2)
        return -exp(-x)*log(x);
    else if (s==3)
        return 2.0*x*x-exp(x);
    else if (s==4)
        return x*x*x*x-14*x*x*x+60.0*x*x-70.0*x;
    else if (s==5)
    {
        if(x>=0) return 4.0*x*x*x-3.0*x*x*x*x;
        else return 4.0*x*x*x+3.0*x*x*x*x;
    }
    else if (s==6)
        return x*x+2.0*x;
    else if (s==7)
        return 2.0*x*x+16.0/x;
    else if (s==8)
        return (10.0*x*x*x+3.0*x*x+x+5.0)*(10.0*x*x*x+3.0*x*x+x+5.0);
    else if (s==9)
        return 3.0*x*x+12.0/(x*x*x)-5.0;
}

double df(double x,int s)
{
       if (s==1)
        return 4*x-3*exp(-x);
    else if (s==2)
        return exp(-x)*(log(x)/x);
    else if (s==3)
        return 4*x-exp(x);
    else if (s==4)
        return 4*pow(x,3)-42*pow(x,2)+120*x-70;
    else if (s==5)
    {
        if(x>=0) return 12*pow(x,2)-12*pow(x,3);
        else return 12*pow(x,2)+12*pow(x,3);
    }
    else if (s==6)
        return 2*x+2;
    else if (s==7)
        return 4*x-(16/(x*x));
    else if (s==8)
        return 2*(10*pow(x,3)+3*x*x+x+5)*(30*x*x+6*x+1);
    else if (s==9)
        return 6*x-(36/pow(x,4));
}

void switchvar(int s)
{
    switch(s)
    {
        case 1: x1=1; e=0.001; break;
        case 2: x1=0; e=0.0001; break;
        case 3: x1=1; e=0.003; break;
        case 4: x1=2; e=0.01; break;
        case 5: x1=0.4; e=0.001; break;
        case 6: x1=4; e=0.01; break;
        case 7: x1=1; e=0.01; break;
        case 8: x1=2; e=0.01; break;
        case 9: x1=0.5; e=0.01; break;
    }
}
int swann(double &a, double &b, int &k, int s) //метод Свена
{
    double h=x1==0?0.01:0.01*x1;
    double x2=x1+h;
    int t;
    if(f(x2, s) > f(x2-h, s)) h = -h;
    k = 1;

    while(1)
    {
        h=2*h;
        x2=x2+h;
        if(f(x2,s)>f(x2-h,s)) break;
        a=x2-h;
        k++;
    }
    b=x2;
    if (a>b)
    {
        t=b;
        b=a;
        a=t;
    }
    /*if(x2-h<x2) { a=x2-h; b=x2; }
    else { a=x2; b=x2-h; }*/
    return k;
}
int swann2(double &a, double &b, int &k, int s)
{
    double x2,t,h;
    h=x1==0?0.01:x1*0.01;
    x2=x1+h;
    if(df(x1,s)>0) h=-h;
    k = 1;
    while(1)
    {
        h=2*h;
        x2=x2+h;
        if(df(x2,s)*df(x2-h,s)<0) break;
        a=x2-h;
        k++;
        //system("pause");
    }
    if(x2-h<x2) { a=x2-h; b=x2; }
    else { a=x2; b=x2-h; }
    /*if (a>b)
    {
        t=b;
        b=a;
        a=t;
    }*/

    return k;

}
double dichotomy(double &a, double &b, int &k, double s)
{
    double d=e*0.1;
    double a1,b1;
    k=0;
    while(k < 5)
    {
        a1=(a+b-d)/2;
        b1=(a+b+d)/2;
        if(f(a1,s) < f(b1,s)) b=b1;
        else a=a1;
        k++;
    }
     return((a+b)/2);
}

double bolcano(double &a, double &b, int &k, int s)
{
    double x=(a+b)/2;
    k=1;
    while(fabs(df(x,s))>e && fabs(b-a)>e/*k<6*/)
    {
        x=(a+b)/2;
        if(df(x,s)>0) b=x;
        else a=x;
        k++;
    }
    return x;
}

double kub_int(double &a, double &b, int &k, double s)
{
    double z=df(a,s)+df(b,s)+3*(f(a,s)-f(b,s))/(b-a);
    double w=pow(z*z-df(a,s)*df(b,s),0.5);
    double Y=(z-df(a,s)+w)/(df(b,s)-df(a,s)+2*w);
    double x=a+Y*(b-a);
    //double x=d;
    k=1;
    while(fabs(df(x,s))>e && x!=a && x!=b)
    {
        if(df(x,s)>0) b=x;
        else a=x;
        z=df(a,s)+df(b,s)+(3*(f(a,s)-f(b,s)))/(b-a);
        w=pow(z*z-df(a,s)*df(b,s),0.5);
        Y=(z-df(a,s)+w)/(df(b,s)-df(a,s)+2*w);
        x=a+Y*(b-a);
        k++;
    }
    return x;//=(a+b)/2.0;
}


int main()
{
    double a,b,x;
    int s=6;
    int k;
    switchvar(s);

    //Свенн
    k=swann(a,b,k,s);
    cout<<endl<<"Swann-dichotomy:"<<endl;
    cout << "func #" << s << ": a=" << a << "  " << "b=" << b << " || k=" << k << endl;
    x=dichotomy(a,b,k,s);
    cout << "dichotomy xmin=" << x << " || k=" << k << endl;

    //k=0; a=0; b=0;

    // кубическая интерполяция
    cout << "\nSwann-2 - dichotomy - kub_int:\n";
    k=swann2(a,b,k,s); //Метод Свенна-2
    cout << "Swann-2: a=" << a << " b=" << b << " || k=" << k << endl;
    x=dichotomy(a,b,k,s); // 5 шагов
    //x=bolcano(a,b,k,s);
    cout << "Bolcano: a=" << a << " b=" << b << " || k=" << k << endl;
    x=kub_int(a,b,k,s); // кубическая интерполяция
    cout << "x=" << x << " || k=" << k;


    return 0;
}