#include<iostream>
using namespace std;

double foo(double x,double c3,double c2,double c1,double c0)
{
	return c3*x*x*x+c2*x*x+c1*x+c0;
}

void CurveCut();

void NewTon();

int main(int args,char* argv[])
{
	//x(k+1) = x(k)-f(xk)/f'(xk);
	//
	cout<<"請選擇 解方程的方法 :";
	cout<<endl<<"1---NewTon ,2----弦割法";
	int method = 1;
	cin>>method;
	switch(method)
	{
	case 1:
		NewTon();
		break;
		case 2:
			CurveCut();
		break;	
	default:
		break ;
	}
	return 0;
	
/*	double c3,c2,c1,c0;
	cout<<"請按次序輸入 三次多項式的系數(shù)"<<endl;
	cout<<"例如y=(x)^3-3x-1，請按順序輸入 1 空格 0 控制 -3 空格 -1 空格 ";
	cin>>c3>>c2>>c1>>c0;

	//求導(dǎo)數(shù)
	double cd2,cd1,cd0;
	cd2 = 3*c3;
	cd1 = 2*c2;
	cd0 = c1;


	double xk = 2;
	cout<<"請輸入初始迭值 x0=";
	cin>>xk;

	double df = 2.0;
	while (df > 0.0001 )
	{
		df = foo(xk,c3,c2,c1,c0) / foo(xk,0,cd2,cd1,cd0);
		xk -= df;
	}

	cout<<"\n結(jié)果是x"<<xk;
	cout<<endl;
	
	//下面執(zhí)行弦割法
	double xk_1 = 1.9;
	xk = 2.0;
	

	return 0;*/
}

void NewTon()
{
	double c3,c2,c1,c0;
	cout<<"請按次序輸入 三次多項式的系數(shù)"<<endl;
	cout<<"例如y=(x)^3-3x-1，請按順序輸入 1 空格 0 控制 -3 空格 -1 空格\n ";
	cin>>c3>>c2>>c1>>c0;

	//求導(dǎo)數(shù)
	double cd2,cd1,cd0;
	cd2 = 3*c3;
	cd1 = 2*c2;
	cd0 = c1;


	double xk = 2;
	cout<<"請輸入初始迭值 x0=";
	cin>>xk;

	double df = 2.0;
	while (df > 0.0001 )
	{
		df = foo(xk,c3,c2,c1,c0) / foo(xk,0,cd2,cd1,cd0);
		xk -= df;
	}

	cout<<"\n結(jié)果是 x = "<<xk;
	cout<<endl;

}
void CurveCut()
{
	double c3,c2,c1,c0;
	cout<<"請按次序輸入 三次多項式的系數(shù)"<<endl;
	cout<<"例如y=(x)^3-3x-1，請按順序輸入 1 空格 0 控制 -3 空格 -1 空格 \n";
	cin>>c3>>c2>>c1>>c0;

	//求導(dǎo)數(shù)
	double cd2,cd1,cd0;
	cd2 = 3*c3;
	cd1 = 2*c2;
	cd0 = c1;


	double xk = 2;
	cout<<"請輸入初始迭值 x0=";
	cin>>xk;

	double xk_1 = 2;
	cout<<"請輸入初始迭值 x1=";
	cin>>xk_1;
	

	double df = 2.0;
	while (df > 0.0001 )
	{
		double fxk = foo(xk,c3,c2,c1,c0) ;
		double fxk_1=  foo(xk_1,c3,c2,c1,c0) ;
		df = (xk-xk_1)*(fxk/(fxk-fxk_1)) ;
		xk_1 = xk;
		xk -= df;
	}

	cout<<"\n結(jié)果是 x = "<<xk;
	cout<<endl;
}