ODY.R-K-2

#include <iostream.h>
#include <iomanip.h>
#include <math.h>
#include <stdio.h>

double F1(double x,double y1, double y2)
{
    return (y1*exp(x))/(x*y2);
}

double F2(double x, double y1, double y2)
{
    return 2*y1+y2-4*x;
}

void main(void)
{
    int a=1, b=4;
    int k;
    double n,h,x;
    double Y1,Y2;
    double y1app[1001],y2app[1001];
    cout<<"n="; cin>>n;
    h=(b-a)/n;
    y1app[1]=2;
    y2app[1]=exp(1);
    k=0;
    x=a;
    cout<<"x"<<setw(9)<<"y1"<<setw(12)<<"y1app"<<setw(10)<<"y1app-y1"<<setw(1)<<"y2"<<setw(11)<<"y2app"<<setw(11)<<"y2app-y2"<<endl;
    cout<<"________________________________________________________"<<endl;
    while(k<=n)
    {
        k++;
        Y1=y1app[k]+(h/2)*F1(x,y1app[k],y2app[k]);
        Y2=y2app[k]+(h/2)*F2(x,y1app[k],y2app[k]);
        y1app[k+1]=y1app[k]+h*F1(x+h/2,Y1,Y2);
        y2app[k+1]=y2app[k]+h*F2(x+h/2,Y1,Y2);
        double y1tochn=2*x;
        double y2tochn=exp(x);
        printf("%5.4f\t%4.4f\t%4.4f\t%5.4f\t%4.4f\t%4.4f\t%5.4f\n",x,y1tochn,y1app[k],fabs(y1app[k]-y1tochn),y2tochn,y2app[k],fabs(y2app[k]-y2tochn));
        x+=h;
    }
    cout<<"Shag="<<h<<endl;
}