Построение графика в Exel по данным из файла полученного в ходе выполнения программы

#include "stdafx.h"
 
 
#include <iostream>
#include <fstream>
#include <iomanip>
#include <math.h>
 
using namespace std;
 
int n;
double f, fi, R1, R2, R3, R4, R5, R6, t0, t1, t2, L, C, h, hz, E0, w, pi, D1, D2, D3, FI, FU, T1, T2, R7, B1, B2, B3, FIz, FUz;
double I[2000], U[2000], t[2000], tz[2000], Iz[2000], Uz[2000];
double E(double tl)
{
    if (tl>t1) { return 0; }
    else { return E0 + E0*sin(w*tl + fi); }
}
double fI(double tl, double Il, double Ul)
{
    return (1/(L*D1))*(L*D2*E(tl)+E(tl)*(D3*R4+((R2*(R6+R7))/(R7*(R1+R2))))- Il*(R6+D1*R4+((L*D2)/C)+((R6+R7)/R7)*(R3+((R1*R2)/(R1+R2))))- Ul*(D2*R4+((R7+R6)/R7)));
}
double fU(double tl, double Il, double Ul)
{
    return (1 / C)*(Il);
}
double fIz(double tzl, double Izl, double Uzl)
{
    return -Izl *(B1/B3)-Uzl*(B2/B3);
}
double fUz(double tzl, double Izl, double Uzl)
{
    return (1 / C)*(Izl);
}
int main()
{
    setlocale(LC_ALL, "Russian");
    int i;
    pi = acos(-1.0);
    f = 15;
    fi = 0;
    R1 = 32;
    R2 = 22;
    R3 = 48;
    R4 = 1.75;
    R5 = 16;
    R6 = 10;
    R7 = 25.6;
    t0 = 0;   t1 = 0.2;   t2 = 0.4;
    E0 = 30;     L = 10.3*pow(10.0, -3);    C = 28 * pow(10.0, -6);
    w = 2 * pi*f; n = 2000;    h = (t1 - t0) / n;
    cout << endl;
    cout << "h= " << h << endl;
    cout << endl;
    cout << "i=" << setw(15) << "t=" << setw(15) << "I(t)=" << setw(15) << "U(t)=" << endl;
    U[1] = 0; I[1] = 0; t[1] = 0;
    D1 = 1+((R3+R6)/R5)+((R1*R2)/((R1+R2)*R5))+((R5+R6)/(R5*R7))*(((R1*R2)/(R1+R2))+R3);  
    D2 = (1 / R5)+((R5-R6)/(R5*R7));  
    D3 = (R2*(R5+R6))/(R5*R7*(R1+R2))+((R2)/(R1*R5));
    ofstream f,fx;
    f.open("file.txt");
    fx.open("file.xls");
    f << "i" << setw(15) << "t[i]" << setw(15) << "I[i]" << setw(15) << "U[i]" << endl;
    fx << "i" << "\t" <<  "\t" << "t[i]" << "\t" << "\t"  << "I[i]" << "\t" << "\t" << "U[i]" << endl;
    
    for (i = 0; i <= n; i++)
    {
        t[i + 1] = t[i] + h;
        FI = fI(t[i], I[i], U[i]);
        FU = fU(t[i], I[i], U[i]);
        I[i + 1] = I[i] + h *( U[i]+ (h/2)*FI);
        U[i + 1] = U[i] +h*fI(t[i]+(h/2),I[i]+(h/2)*U[i],U[i]+(h/2)*FU) ;
        cout << i << setw(15) << t[i] << setw(15) << I[i] << setw(15) << U[i] << endl;
        f << i << setw(15) << t[i] << setw(15) << I[i] << setw(15) << U[i] << endl;
        fx << i << "\t" << "\t" << t[i] << "\t" << "\t" << I[i] << "\t" << "\t" << U[i] << endl;
    }
    f.close(); fx.close();
    ofstream z, zx;
    z.open("file2.txt");
    zx.open("file2.xls");
    cout << "Без учета E(t)" << endl;
    z << "Без учета E(t)" << endl;
    zx << "Без учета E(t)" << endl;
    cout<< "i" << setw(15) << "t[i]" << setw(15) << "I[i]" << setw(15) << "U[i]" << endl;
    z << "i" << setw(15) << "t[i]" << setw(15) << "I[i]" << setw(15) << "U[i]" << endl;
    zx << "i" << "\t" << "\t" << "t[i]" << "\t" << "\t" << "I[i]" << "\t" << "\t" << "U[i]" << endl;
    Uz[0] = U[2000]; Iz[0] = I[2000]; tz[0] = t[2000];
    B1 = (((R3 + R2)*R5) / (R5 + R6)) + (R4 + ((R5*R6) / (R5 + R6)))*(((R5 + R6)*(R7 + R3 + R2)) / (R5*R7) + ((R3 + R2) / R5)) + (L / C)*((R5 + R6 + R7) / (R5*R7));
    B2 = (R5 / (R5 + R6)) + (R4 + ((R5*R6) /( R5 + R6)))*((R5 + R6 + R7) / (R5*R7));
    B3 = L*(((R5 + R6)*(R7 + R3 + R2) + R7*(R3 + R2)) / (R5*R7));
    hz = (t2 - t1) / n;
    for (i = 0; i <= n; i++)
    {
        tz[i + 1] = tz[i] + hz;
        FIz = fIz(tz[i], Iz[i], Uz[i]);
        FUz = fUz(tz[i], Iz[i], Uz[i]);
        Iz[i + 1] = Iz[i] + hz *(Uz[i] + (hz / 2)*fIz(tz[i],Iz[i],Uz[i]));
        Uz[i + 1] = Uz[i] + hz*fIz(tz[i] + (hz / 2), Iz[i] + (hz / 2)*Uz[i], Uz[i] + (hz / 2)*fUz(tz[i],Iz[i],Uz[i]));
        cout << i << setw(15) << tz[i] << setw(15) << Iz[i] << setw(15) << Uz[i] << endl;
        z << i << setw(15) << tz[i] << setw(15) << Iz[i] << setw(15) << Uz[i] << endl;
        zx << i << "\t" << "\t" << tz[i] << "\t" << "\t" << Iz[i] << "\t" << "\t" << Uz[i] << endl;
    }
    z.close();
    zx.close();
 
    return 0;
}