Optima3Tasks

// Lst3Tasks.cpp: определяет точку входа для консольного приложения.
//

#include "stdafx.h"
#include <iostream>
#include <string>
#include <math.h>
#include <Windows.h>

using namespace std;

double f(double x)
{
    return (3 * cos(x)*x);
}

void doubleDots(double left, double right)
{
    double eps = 0.07f;
    double a = left; double b = right;
    double x1, x2;
    int count = 0;
    x1 = (a + b - eps) / 2;
    x2 = (a + b + eps) / 2;
    while (count < 10)
    {
        count++;
        if (f(x1) < f(x2))
            {

                b = x2;
                x1 = (a + b - eps) / 2;
                x2 = (a + b + eps) / 2;
            }
        else
            {
                a = x1;
                x1 = (a + b - eps) / 2;
                x2 = (a + b + eps) / 2;
            }
    }
    cout << "xmin = " << (a + b) / 2 << "\nf(xmin) = " << f((a + b) / 2) << "\n";
}
void fibonaci(double left, double right)
{
    int arr[13] = { 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233 };
    double a, b, eps, x1, x2;
    eps = 0.01f; a = left; b = right;
    x1 = ((b - a) * 233 - eps) / 377 + a;
    x2 = a - x1 + b;
    int i = 12; int j = 11;
    while (i)
    {
        if (f(x2) > f(x1))
        {
            if (x2 > x1)
            {
                b = x2;
                x1 = ((b - a) * arr[j] - eps) / arr[i] + a;
                x2 = a - x1 + b;
            }
            else
            {
                a = x2;
                x1 = ((b - a) * arr[j] - eps) / arr[i] + a;
                x2 = a - x1 + b;
            }
        }
        else
        {
            if (x1 > x2)
            {
                b = x1;
                x1 = x2;
                x2 = a - x1 + b;
            }
            else
            {
                a = x1;
                x1 = x2;
                x1 = ((b - a) * arr[j] - eps) / arr[i] + a;
            }
        }
        i--; j--;
    }
    if (!i)
    {
        cout << "xmin = " << (a + b) / 2 << "\nf(xmin) = " << f((a + b) / 2) << "\n";
        return;
    }
}
void kvInterpol(double left, double right)
{
    double a;
    a = (right - left) / 2 + (right - left) / 6.5f + left;
    double x1, x2, x3, y1, y2, y3;
    double h = 0.0005; double eps = 0.07; double xmin;
    x1 = a - h;
    x2 = a;
    x3 = a + h;
    y1 = f(x1);
    y2 = f(x2);
    y3 = f(x3);

    xmin = 0.5f * ((x2 * x2 - x3 * x3) * f(x1) + (x3 * x3 - x1 * x1) * f(x2) + (x1 * x1 - x2 * x2) * f(x3)) /
        ((x2 - x3) * f(x1) + (x3 - x1) * f(x2) + (x1 - x2) * f(x3));

    while (abs(f(a) - f(xmin)) >= eps)
    {
        a = xmin;
        x1 = a - h;
        x2 = a;
        x3 = a + h;
        y1 = f(x1);
        y2 = f(x2);
        y3 = f(x3);
        xmin = 0.5f * ((x2 * x2 - x3 * x3) * f(x1) + (x3 * x3 - x1 * x1) * f(x2) + (x1 * x1 - x2 * x2) * f(x3)) /
            ((x2 - x3) * f(x1) + (x3 - x1) * f(x2) + (x1 - x2) * f(x3));
    }

    cout << "xmin = " << xmin << "\nf(xmin) = " << f(xmin) << "\n";
}

int main()
{
    double left, right;
    cout << "f(x) = 3*cos(x)*x\n";
    cout << "Input the left edge\n"; cin >> left;
    cout << "\nInput the right edge\n"; cin >> right;
    if (left > right)
    {
        double *buf = new double;
        *buf = left;
        left = right;
        right = *buf;
        delete buf;
    }
    doubleDots(left, right);
    fibonaci(left, right);
    kvInterpol(left, right);
    return 0;
}