Gửi FB Anh Hai

Main.cpp

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


using namespace std;


// Hang so e
// Duoc dung neu F(x) = 0 co chua e.
//VD: x * pow(e, x) - 1 = 0
const double e		= 2.718281828459;

// So lan lap lai toi da
int maxLoop	= 100;

// Gia tri do chinh xac
double epsilon	= 0.0001;



// Dinh nghia ham F(x) = 0 tai day
#define F(x) (  pow(x,3) - pow(x,2) -2  )

// Dao ham cua F(x), chinh la F'(x) tai day
#define Fd(x) (  3*pow(x,2) - 2*x  )

// Dinh nghia F(x) dung trong phuong phap successive approximations
#define F1(x) ( pow(x,3) - pow(x,2) -2 )


/* 
 * Phuong phap Newton's de giai phuong trinh F(x) = 0
 * Output: 
 * x - Nghiem gan dung nhat cua phuong trinh
 * Return:
 * So lan lap da su dung
 */
int NewtonMethodForEquation(double& x)
{
	int n = 1;

	while( ( fabs(F(x)) > epsilon ) && ( n <= maxLoop ) )
	{
		x = x - ( F(x) / Fd(x) );

		n++;
	}


	return n;
}


/* 
 * Phuong phap Secant de giai phuong trinh F(x) = 0
 * Input:
 * x0 - Nghiem gan dung thu nhat
 * x1 - Nghiem gan dung thu hai
 * Output:
 * x - Nghiem gan dung nhat cua phuong trinh
 * Return:
 * So lan lap da su dung
 */
int SecantMethodForEquation(double& x, double x0, double x1)
{
	int n = 2;

	while( ( fabs(F(x1)) > epsilon ) && ( n <= maxLoop ) )
	{
		x = x1 - (F(x1) * (x1 - x0)) / (F(x1) - F(x0));
		x0 = x1;
		x1 = x;

		n++;
	}


	return n;
}

/* 
 * Phuong phap Successive approximations de giai phuong trinh F(x) = x
 * Output:
 * x - Nghiem gan dung nhat cua phuong trinh
 * Return:
 * So lan lap da su dung
 */
int SuccessiveApproxForEquation(double& x)
{
	int n = 1;

	while( ( fabs(x - F1(x)) > epsilon ) && ( n <= maxLoop ))
	{
		x = F1(x);

		n++;
	}


	return n;
}

int main()
{
	cout<<"\nGIAI PHUONG TRINH PHI TUYEN";
	cout<<"\nNhap do chinh xac epsilon: ";
	cin>>epsilon;
	cout<<"\nNhap so lan lap toi da: ";
	cin>>maxLoop;
	
	double x; // Luu nghiem
	int n; // Luu so lan lap
	/* Vi du su dung Newton Method */
	cout << "\nNewton's method: " << endl << endl;

	cout << "Nhap nghiem ban dau gan dung: ";
	cin >> x;
	n = NewtonMethodForEquation(x);
	if(n > maxLoop)
		cout << "Trong " << maxLoop << " buoc lap, khong the tim thay ket qua!" << endl;
	else
		cout << "Ket qua la : " << x << " va tim duoc trong " 
			 << n << " buoc lap!" << endl;



	double x0, x1;


	/* Vi du su dung Secant Method */
	cout << "\nSecant method: " << endl << endl;

	cout << "Nhap nghiem gan dung thu nhat: ";
	cin >> x0;

	cout << "Nhap nghiem gan dung thu hai: ";
	cin >> x1;

	n = SecantMethodForEquation(x, x0, x1);

	if(n > maxLoop)
		cout << "Trong " << maxLoop << " buoc lap, khong the tim thay ket qua!" << endl;
	else
		cout << "Ket qua la : " << x << " va tim duoc trong " 
			 << n << " buoc lap!" << endl;


	/* Vi du su dung Successive Approximations Method */
	cout << "\nSuccessive approximations method: " << endl << endl;

	cout << "Nhap nghiem ban dau gan dung: ";
	cin >> x;


	n = SuccessiveApproxForEquation(x);

	if(n > maxLoop)
		cout << "Trong " << maxLoop << " buoc lap, khong tim thay ket qua!" << endl;
	else
		cout << "Ket qua la: " << x << " va tim duoc trong " 
			 << n << " buoc lap!" << endl;

	getch();
	return 0;
}