lab4-veronika-true

#include <iostream>
#include <string>
#include <cmath>
#include <iomanip>
#include <limits>

int checkForBadFormat(std::string);
double fact(double);
double E(double, double);
double sec(double, double);
void printStr(double, double);

std::string modifyString(std::string);

int main() {
    setlocale(LC_CTYPE, "Russian");

    std::string tempString;

    double absError = 0;
    double xMin = 1.7;
    double xMax = 1.7;
    double step = 0;
    double xIdeal = 1.7;


    do {
        std::cout << "Введите точность E от 10^(-7) до 10^(-1): ";
        std::cin >> tempString;

        if (modifyString(tempString).size() != 0) {
            absError = std::stod(modifyString(tempString));
        }
        else {
            std::cout << "Введите корректное значение!\n";

            continue;
        }

        if (absError < pow(10, -7) || absError > pow(10, -1) || checkForBadFormat(tempString)) {
            std::cout << "Введите корректное значение!\n";
        }

    } while (absError < pow(10, -7) || absError > pow(10, -1) || checkForBadFormat(tempString));

    do {
        std::cout << "Введите x_start: ";
        std::cin >> tempString;

        if (modifyString(tempString).size() != 0) {
            xMin = std::stod(modifyString(tempString));
        }
        else {
            std::cout << "Введите корректное значение!\n";

            continue;
        }

        if (xMin < -1.57 || xMin > 1.57 || checkForBadFormat(tempString)) {
            std::cout << "Введите корректное значение!\n";
        }

    } while (xMin < -1.57 || xMin > 1.57 || checkForBadFormat(tempString));

    do {
        std::cout << "Введите xEnd: ";
        std::cin >> tempString;

        if (modifyString(tempString).size() != 0) {
            xMax = std::stod(modifyString(tempString));
        }
        else {
            std::cout << "Введите корректное значение!\n";

            continue;
        }

        if (xMax < -1.57 || xMax > 1.57 || checkForBadFormat(tempString)) {
            std::cout << "Введите корректное значение!\n";
        }

    } while (xMax < -1.57 || xMax > 1.57 || checkForBadFormat(tempString));

    bool flag = false;

    do {
        std::cout << "Введите шаг: ";
        std::cin >> tempString;


        if (modifyString(tempString).size() != 0) {
            step = std::stod(modifyString(tempString));
            flag = false;
        }
        else {
            std::cout << "Введите корректное значение!\n";
            flag = true;
            continue;
        }


        if (flag || (std::fabs(xMax - xMin) >= std::numeric_limits<double>::epsilon() && std::fabs(step) < std::numeric_limits<double>::epsilon()) || (step < 0 && xMin < xMax) || (step > 0 && xMin > xMax) || checkForBadFormat(tempString)) {
            std::cout << "Введите корректное значение!\n";
        }

    } while (flag || (std::fabs(xMax - xMin) >= std::numeric_limits<double>::epsilon() && std::fabs(step) < std::numeric_limits<double>::epsilon()) || (step < 0 && xMin < xMax) || (step > 0 && xMin > xMax) || checkForBadFormat(tempString));


    printf("_________________________________________________________________________________________________\n");
    printf("|           x           |         f(x)          |        F(x)           |          del          |\n");
    printf("|_______________________|_______________________|_______________________|_______________________|\n");

    bool pFlag = false;

    if (xMax > xMin) {
        for (double x = xMin; x <= xMax; x = round((x + step) * 100000000) / 100000000) {

            if (std::fabs(x - xMax) < pow(10, -7)) {
                pFlag = true;
                break;
            }

            printStr(x, absError);
        }

        if (pFlag) {
            printStr(xMax, absError);
        }
    }
    else {
        for (double x = xMin; x >= xMax; x = round((x + step) * 100000000) / 100000000) {
            if (std::fabs(x - xMax) < pow(10, -7)) {
                pFlag = true;
                break;
            }
            std::cout << "oao" << std::endl;

            printStr(x, absError);
        }
        if (pFlag) {
            printStr(xMax, absError);
        }
    }


    std::cout << "\n\n";

    do {
        std::cout << "Введите Xideal: ";
        std::cin >> tempString;

        if (modifyString(tempString).size() != 0 && !checkForBadFormat(tempString)) {
            xIdeal = std::stod(modifyString(tempString));
        }
        else {
            std::cout << "Введите корректное значение!\n";

            continue;
        }

    } while (xIdeal < -1.6 || xIdeal >= 1.6 || checkForBadFormat(tempString));

    double systemAnswer = 1 / cos(xIdeal);

    printf("_________________________________________________________________________________________________\n");
    printf("|           e           |         f(x)          |        F(x)           |          del          |\n");
    printf("|_______________________|_______________________|_______________________|_______________________|\n");
    for (double i = 0.1; i > 0.0000001; i /= 10)
    {
        printf("| %-15.7f       | %-15.6f       | %-15.6f       | %-15.6f       |\n", i, sec(xIdeal, i), systemAnswer, sqrt(fabs(sec(xIdeal, i) * sec(xIdeal, i) - systemAnswer * systemAnswer)));
        printf("|_______________________|_______________________|_______________________|_______________________|\n");
    }
}

int checkForBadFormat(std::string a) {
    return a[0] == '.' || (a[0] == '-' && a[1] == '.');
}

double fact(double N)
{
    if (N < 0)
        return 0;
    if (N == 0)
        return 1;
    else
        return N * fact(N - 1);
}

double E(double n, double absError) {
    double res = std::pow(2, 2 * n + 2) * fact(2 * n) / std::pow(atan(1) * 4, 2 * n + 1);
    double summ = 0;
    double la = 0, a = 0;

    int k = 0;
    while (true) {
        la = a;
        a = pow(-1, k % 2) / pow(2 * k + 1, 2 * n + 1);
        if (isnan(a + summ) || !isfinite(a + summ) || abs(abs(a) - abs(la)) < absError) break;
        summ += a;
        k++;
    }

    if (isnan(summ * res) || !isfinite(summ * res)) return 1;

    return summ * res;
}

double sec(double x, double absError) {
    double pi = atan(1) * 4;
    double summ = E(0, absError);
    double last_a = 0, a = E(0, absError);
    double n = 1;

    do {
        last_a = a;
        a *= fabs(E(n, absError) / E(n - 1, absError)) * x * x /
            static_cast<double>(2 * n) / static_cast<double>(2 * n - 1);
        summ += a;
        ++n;
    } while (absError <= fabs(fabs(a) - fabs(last_a)));

    return summ;
}

std::string modifyString(const std::string st) {
    std::string newStr = "";

    for (size_t i = 0; i < st.size(); i++) {
        if ((st[i] >= '0' && st[i] <= '9') || st[i] == '.' || st[i] == '-') {
            newStr += st[i];
        }
        else {
            return "";
        }
    }

    if (newStr == "." || newStr == "-") {
        return "";
    }

    return newStr;
}

void printStr(double x, double absError) {
    double systemAnswer = 1 / cos(x);

    printf("| %-15f       | %-15f       | %-15f       | %-15f       |\n", x, sec(x, absError), systemAnswer, sqrt(fabs(sec(x, absError) * sec(x, absError) - systemAnswer * systemAnswer)));
    printf("|_______________________|_______________________|_______________________|_______________________|\n");
}