mp-units/example/capacitor_time_curve.cpp

/*
 Copyright (c) 2003-2020 Andy Little.

 This program is free software: you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
 the Free Software Foundation, either version 3 of the License or
 (at your option) any later version.

 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 GNU General Public License for more details.

 You should have received a copy of the GNU General Public License
 along with this program. If not, see http://www.gnu.org/licenses./
*/

/*
    capacitor discharge curve using compile_time
    physical_quantities
*/

#include <units/physical/si/capacitance.h>
#include <units/physical/si/resistance.h>
#include <units/physical/si/time.h>
#include <units/physical/si/voltage.h>
#include <cmath>
#include <iostream>

namespace {
namespace voltage {

template<typename Rep = double>
using V = units::si::voltage<units::si::volt, Rep>;

template<typename Rep = double>
using mV = units::si::voltage<units::si::millivolt, Rep>;

template<typename Rep = double>
using uV = units::si::voltage<units::si::microvolt, Rep>;

template<typename Rep = double>
using nV = units::si::voltage<units::si::nanovolt, Rep>;

template<typename Rep = double>
using pV = units::si::voltage<units::si::picovolt, Rep>;

}  // namespace voltage
}  // namespace

using namespace units::si::literals;

int main()
{
  std::cout << "mpusz/units capacitor time curve example...\n";
  std::cout.setf(std::ios_base::fixed, std::ios_base::floatfield);
  std::cout.precision(3);

  constexpr auto C = 0.47uF;
  constexpr auto V0 = 5.0V;
  constexpr auto R = 4.7kR;

  for (auto t = 0ms; t <= 50ms; ++t) {
    const auto Vt = V0 * std::exp(-t / (R * C));

    std::cout << "at " << t << " voltage is ";

    if (Vt >= 1V)
      std::cout << Vt;
    else if (Vt >= 1mV)
      std::cout << voltage::mV<>{Vt};
    else if (Vt >= 1uV)
      std::cout << voltage::uV<>{Vt};
    else if (Vt >= 1nV)
      std::cout << voltage::nV<>{Vt};
    else
      std::cout << voltage::pV<>{Vt};
    std::cout << "\n";
  }
}