#include <iostream>
#include <cmath>
#include <ctime>
#include <fstream>
#include <iomanip>
using namespace std;


double f(double);
double fa(double);


int main()
{
	const int nm = 2;
	double *YE, *YB, *YB50, *OS1E, *OS2E, *OS1B, *OS2B, t = 0, k = 0, h1 = 0.2, h2 = 0.02, w = 1, *w4;
	ofstream fout;
	char fname[15] = "Ish_dannye.txt";



	char const* pS[nm] = { "1. Diffury.",
		"0. Exit."
	};
	int v;
	do
	{
		cout << "\nMenu\n";
		for (int i = 0; i < nm; i++) cout << pS[i] << endl;
		cout << "\nYour choice - > ";
		cin >> v;
		cin.get();

		switch (v)
		{
		case 1:
			cout << "\n" << pS[0] << "\n\n";


			YE = new double[500];
			YB = new double[500];
			YB50 = new double[50];
			OS1E = new double[50];
			OS2E = new double[500];
			OS1B = new double[50];
			OS2B = new double[500];
			w4 = new double[4];

			//Ejler
			YE[0] = 1; OS1E[0] = 0;  OS2E[0] = 0; w4[0] = 1;
			for (int i = 1; i < 500; i++)
			{
				k = k + 0.2; t = t + 0.02;
				if (i < 50)
				{
					YE[i] = w + h1*f(w);
					w = YE[i];
					OS1E[i] = fa(k) - YE[i];
					cout << fa(k) << "   -   " << YE[i] << "    =   " << fa(k) - YE[i] << endl;
					//cin.get();
					if (i < 4)
					{
						w4[i] = YE[i];
					}

				}
				YE[i] = YE[i - 1] + h2*f(YE[i - 1]);
				OS2E[i] = fa(t) - YE[i];
			}
			//Adams-Bawfort
			k = 0.6; t = 0.06;
			YB[0] = 1; OS1B[0] = 0; OS2B[0] = 0; YB50[0] = 1;
			for (int i = 1; i < 500; i++)
			{
				if (i < 4)
				{
					YB[i] = YE[i];
					YB50[i] = w4[i];
					OS1B[i] = OS1E[i]; OS2B[i] = OS2E[i];
					cout << "   -   " << YB50[i] << "  (" << YE[i] << ")   =   " << "_________________" << endl;

					//cin.get();
				}
				else
				{
					t = t + 0.01; k = k + 0.05;
					if (i < 50)
					{
						YB50[i] = YB50[i - 1] + (h1 / 24)*(55 * f(YB50[i - 1]) - 59 * f(YB50[i - 2]) + 37 * f(YB50[i - 3]) - 9 * f(YB50[i - 4])); //метод Адамса
						YB50[i] = YB50[i - 1] + (h1 / 24)*(9 * f(YB50[i]) + 19 * f(YB50[i - 1]) - 5 * f(YB50[i - 2]) + f(YB50[i - 3])); //Метод Башфорта
						OS1B[i] = fa(k) - YB50[i];
						cout << fa(k) << "   -   " << YB50[i] << "  (" << YE[i] << ")   =   " << fa(k) - YB50[i] << endl;
						//cin.get();
					}
					YB[i] = YB[i - 1] + (h2 / 24)*(55 * f(YB[i - 1]) - 59 * f(YB[i - 2]) + 37 * f(YB[i - 3]) - 9 * f(YB[i - 4])); //метод Адамса-Башфорта
					YB[i] = YB[i - 1] + (h2 / 24)*(9 * f(YB[i]) + 19 * f(YB[i - 1]) - 5 * f(YB[i - 2]) + f(YB[i - 3]));
					OS2B[i] = fa(t) - YB[i];
				}
			}

			fout.open(fname);
			fout << "Ejler znachenija:" << endl;
			for (int i = 0; i < 500; i++)
			{
				fout << YE[i] << " ";
			}
			fout << endl << endl;

			fout << "Ejler owibki h1=0.2:" << endl;
			for (int i = 0; i < 50; i++)
			{
				fout << OS1E[i] << " ";
			}
			fout << endl << endl;

			fout << "Ejler owibki h2=0.02:" << endl;
			for (int i = 0; i < 500; i++)
			{
				fout << OS2E[i] << " ";
			}
			fout << endl << endl;

			fout << "Adams-Bawf znachenija:" << endl;
			for (int i = 0; i < 500; i++)
			{
				fout << YB[i] << " ";
			}
			fout << endl << endl;

			fout << "Adams-Bawf owibki h1=0.2:" << endl;
			for (int i = 0; i < 50; i++)
			{
				fout << OS1B[i] << " ";
			}
			fout << endl << endl;

			fout << "Adams-Bawf owibki h2=0.02:" << endl;
			for (int i = 0; i < 500; i++)
			{
				fout << OS2B[i] << " ";
			}
			fout << endl << endl;
			fout.close();

			break;



		case 0:
			delete[] YE;
			delete[] YB;
			delete[] YB50;
			delete[] OS1E;
			delete[] OS2E;
			delete[] OS1B;
			delete[] OS2B;
			delete[] w4;

			break;
		default: cout << "\nIllegal choice\n\n";
		}
	} while (v != 0);



	return 0;
}



double f(double x)
{
	double xy = 0;
	xy = 0.15*x - 0.03*x*x;

	return xy;
}

double fa(double t)
{
	double xya = 0;
	xya = (0.15*exp(0.15*t)) / (0.12 + 0.03*exp(0.15*t));

	return xya;
}