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// ...
int main7() {
	/*
		Глава 3. Раздел 2. Задание 11
		
		Для x, изменяющегося в интервале от x0 до xk с шагом h,
		вычислить значения бесконечной суммы S(x) с точностью e=0.00001 и функции y(x).
	*/


	clearConsole();

	const float e = 0.0001;

	float x0, xk, h;
	float a, s;
	int n;
	
	cout << "Enter x0: ";
	cin >> x0;
	cout << "Enter xk: ";
	cin >> xk;
	cout << "Enter h: ";
	cin >> h;

	clearConsole();

	if (x0 > xk || h <= 0) {
		cout << "arg x0 or xk or h WRONG!" << endl << endl;

		int type;
		cout << "Enter smthng num";
		cin >> type;
		cout << endl;

		return main7();
	}
	

	cout << " ============ " << endl;
	cout << "* S(x) = ...;\ty(x) = ..." << endl;

	cout << " ====== CALC ====== " << endl;

	for (float x = x0; x < xk; x += h) {

		a = 1;
		s = a;
		n = 0;

		while (abs(a) > e) {
						
			a *= -2*x / ( (2 * n+2) * (2 * n + 1) );

			s += a;
			n++;
		}

		float y = 0;
		if (x >= 0)
			y = cos(sqrt(2 * x));

		cout << "  S(" << x << ") = " << s << ";\ty(" << x << ") = " << y << endl;

	}
	

	cout << " ================== " << endl << endl << endl << endl;

	catchExit(main7, 7);

	return 0;
}