#include <array>
#include <cmath>
#include <numbers>

#include <fstream>

template <typename T, std::size_t N> struct signal : public std::array<T, N> {

  constexpr signal() {}

  constexpr signal(float begin, float end) {
    float step = (end - begin) / (N - 1);

    for (std::size_t i = 0; i < N; i++) {
      this->at(i) = begin + i * step;
    }
  }

  constexpr signal(const std::array<T, N> &x, auto fun) {
    for (std::size_t i = 0; i < N; i++) {
      this->at(i) = fun(x.at(i));
    }
  }

  constexpr signal(const signal &sig, auto fun) {
    for (std::size_t i = 0; i < N; i++) {
      this->at(i) = fun(sig.at(i));
    }
  }

  constexpr signal operator+(const T &t) const {
    return signal(*this, [&](T elem) { return elem + t; });
  };

  constexpr signal operator-(const T &t) const {
    return signal(*this, [&](T elem) { return elem - t; });
  };

  constexpr signal operator*(const T &t) const {
    return signal(*this, [&](T elem) { return elem * t; });
  };

  constexpr signal operator/(const T &t) const {
    return signal(*this, [&](T elem) { return elem / t; });
  };

  constexpr signal operator+(const signal &sig) const {
    signal ret;
    for (std::size_t i = 0; i < N; i++) {
      ret.at(i) = this->at(i) + sig.at(i);
    }
    return ret;
  };

  constexpr signal operator-(const signal &sig) const {
    signal ret;
    for (std::size_t i = 0; i < N; i++) {
      ret.at(i) = this->at(i) - sig.at(i);
    }
    return ret;
  };

  friend constexpr signal operator+(const T& t, const signal& sig) {
	return sig + t;
  }

  friend constexpr signal operator*(const T& t, const signal& sig) {
	return sig * t;
  }

  friend constexpr signal operator/(const T& t, const signal& sig) {
    	signal ret;
    	for (std::size_t i = 0; i < N; i++) {
      		ret.at(i) = t / sig.at(i);
    	}
    	return ret;
  }
};

int main() {

  constexpr float A = 1.18090254918130e-3;
  constexpr float B = 2.16884014794388e-4;
  constexpr float C = 1.90058756197216e-6;
  constexpr float D = 1.83161892641824e-8;

  constexpr int c_lut_points = 50;

  constexpr signal<float, c_lut_points> resistance(1e3, 10e3);

  constexpr auto temperature_k = 1 / (A + 
		  		      B * signal(resistance, [](float x) {return std::log(x);}) +
				      C * signal(resistance, [](float x) {return std::pow(std::log(x), 2);}) +
				      D * signal(resistance, [](float x) {return std::pow(std::log(x), 3);}));

  constexpr auto temperature_celsius = temperature_k - 273.15f;

  std::ofstream file("out.csv");
  for(int i = 0; i < c_lut_points; i++) {
	file << resistance[i] << ", " << temperature_celsius[i] << "\n";
  }

  return 0;
}