x002.h

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#pragma once

#include "xconfig.h"
#include <array>
#include <cmath>
#include <fstream>
#include <functional>
#include <iomanip>
#include <iostream>
#include <string>

namespace nmx::apps::x002 {

inline void ex1() {
    //Konfigurationsdaten nutzen
    using namespace nmx::settings;
    //Pfad zu einem Ausgabeverzeichnis benennen
    Config::set_current_dir("x002");
    //Dateiname zu Ausgabe der Werte
    std::string fname = Config::get_current_file(__func__, "dat");

    try {
        std::ofstream fout{ fname };
        // wurde die Datei zum Schreiben geöffnet?
        if (!fout) {
            throw std::ios_base::failure{ fname };
        }
        //Formatierung
        fout << std::scientific << std::setprecision(2);
        //Ausgabe
        for (double x = -2; x <= 2; x += 1) {
            fout << std::setw(9) << x << "," << std::pow(x, 2) //
                 << "," << std::setw(9) << std::pow(x, 3) //
                 << "," << std::setw(9) << std::pow(x, 4) //
                 << "," << std::setw(9) << std::pow(x, 5) << std::endl;
        }

    } catch (std::ios_base::failure ferror) {
        std::cout << "could not open file:" //
                  << ferror.what() << std::endl;
    }
}

auto open_file(const std::string &fname) {
    std::ofstream fout{ fname };
    // wurde die Datei zum Schreiben geöffnet?
    if (!fout) {
        throw std::ios_base::failure{ fname };
    }
    return fout;
}

using RealFN = std::function<double(double)>;

inline void fn_data(std::ofstream &fout,
                    std::initializer_list<RealFN> fnlst,
                    std::array<double, 3> params) {
    //structured bindings jedes Element des Feldes wird
    //einer Variablen zugeordnet
    auto [xmin, xmax, dx] = params;
    for (double x = xmin; x <= xmax; x += dx) {
        // für jedes x
        fout << x;
        for (auto &fn : fnlst) {
            //werden die dazugehörigen Funktionswerte ausgegeben
            fout << "," << fn(x);
        }
        fout << std::endl;
    }
}
inline void ex2() {
    using namespace nmx::settings;
    Config::set_current_dir("x002");
    std::string fname = Config::get_current_file(std::string(__func__) + ".dat");

    auto fn2 = [](double x) { return std::pow(x, 2); };
    auto fn3 = [](double x) { return std::pow(x, 3); };
    auto fn4 = [](double x) { return std::pow(x, 4); };
    auto fn5 = [](double x) { return std::pow(x, 5); };

    try {
        //öffne Ausgabestrom
        auto fout = open_file(fname);
        fout << std::scientific << std::setprecision(2);

        //Berechne und schreibe Funktionsdaten mit xmin = -2,
        // xmax=2 und dx = 0.5
        fn_data(fout, { fn2, fn3, fn4, fn5 }, { -2, 2, 0.5 });

    } catch (std::ios_base::failure ferror) {
        std::cout << "could not open file:" //
                  << ferror.what() << std::endl;
    }
}

} // namespace nmx::apps::x002