gaosi.cpp

用C＋＋语言编写的数值算法程序

#include<iostream.h>
#include<math.h>
#include<iomanip.h>
class euler{
	double low;//下线
	double up;//上线
	double h;//分度值
	double x;//X初值
	double y[100];//记录所得解
public:
	euler(double Low,double Up,double H)
	{
		low=Low;up=Up;h=H;
	}
	void setfirst(double,double);
	double fun(double,double);
	void fixy();
	void print();
};
void euler::setfirst(double X,double Y)
{
	x=X;y[0]=Y;
}
double euler::fun(double x,double y)
{
	return sin(x)+cos(y);
}
void euler::fixy()
{
	int n=(up-low)/h;
	double k1,k2;
	for(int i=0;i<n;i++)
	{   
        k1=fun(x+i*h,y[i]);
		k2=fun(x+i*(h+1),y[i]+h*k1);
		y[i+1]=y[i]+(k1+k2)*h/2;
	}

}
void euler::print()
{
	for(int j=0;j<=(up-low)/h;j++)
	{
		cout<<y[j]<<setw(12);
		if((j+1)%6==0)  cout<<endl;
	}
}
void main()
{
	euler A(2.5,4,0.025);
	A.setfirst(2.5,0);
	A.fixy();
	A.print();
}