forked from mpusz/mp-units
9527b39005
We had some fun exploring the STD UDLs for potential collisions, we have learnt our lesson and know how to proceed. Now is high time to start behaving and obeying C++ rules.
135 lines
4.6 KiB
C++
135 lines
4.6 KiB
C++
/*
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Copyright (c) 2003-2019 Andy Little.
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see http://www.gnu.org/licenses./
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*/
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#include <iostream>
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#include <units/format.h>
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#include "./length.h"
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#include "./volume.h"
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#include "./time.h"
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#include "./area.h"
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#include "./units_str.h"
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using namespace units::physical::si::literals;
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using namespace units::physical::international;
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using namespace units::experimental;
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void simple_quantities()
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{
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using distance = length::m<>;
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using q_time = q_time::s<>;
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constexpr distance km = 1.0_q_km;
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constexpr distance miles = 1.0_q_mi;
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constexpr q_time sec = 1_q_s;
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constexpr q_time min = 1_q_min;
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constexpr q_time hr = 1_q_h;
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std::cout << "A physical quantities library can choose the simple\n";
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std::cout << "option to provide output using a single type for each base unit:\n\n";
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std::cout << km << '\n';
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std::cout << miles << '\n';
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std::cout << sec << '\n';
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std::cout << min << '\n';
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std::cout << hr << "\n\n";
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}
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void quantities_with_typed_units()
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{
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constexpr length::km<> km = 1.0_q_km;
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constexpr length::mi<> miles = 1.0_q_mi;
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constexpr q_time::s<> sec = 1_q_s;
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constexpr q_time::min<> min = 1_q_min;
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constexpr q_time::h<> hr = 1_q_h;
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std::cout << "A more flexible option is to provide separate types for each unit,\n\n";
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std::cout << km << '\n';
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std::cout << miles << '\n';
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std::cout << sec << '\n';
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std::cout << min << '\n';
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std::cout << hr << "\n\n";
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constexpr length::m<> meter = 1_q_m;
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std::cout << "then a wide range of pre-defined units can be defined and converted,\n"
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" for consistency and repeatability across applications:\n\n";
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std::cout << meter << '\n';
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std::cout << " = " << length::AU<>(meter) << '\n';
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std::cout << " = " << length::angstrom<>(meter) << '\n';
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std::cout << " = " << length::ch<>(meter) << '\n';
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std::cout << " = " << length::fathom<>(meter) << '\n';
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std::cout << " = " << length::fathom_us<>(meter) << '\n';
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std::cout << " = " << length::ft<>(meter) << '\n';
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std::cout << " = " << length::ft_us<>(meter) << '\n';
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std::cout << " = " << length::in<>(meter) << '\n';
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std::cout << " = " << length::ly<>(meter) << '\n';
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std::cout << " = " << length::mi<>(meter) << '\n';
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std::cout << " = " << length::mi_naut<>(meter) << '\n';
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std::cout << " = " << length::pc<>(meter) << '\n';
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std::cout << " = " << length::pica_comp<>(meter) << '\n';
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std::cout << " = " << length::pica_prn<>(meter) << '\n';
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std::cout << " = " << length::point_comp<>(meter) << '\n';
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std::cout << " = " << length::point_prn<>(meter) << '\n';
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std::cout << " = " << length::rd<>(meter) << '\n';
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std::cout << " = " << length::yd<>(meter) << '\n';
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}
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void calcs_comparison()
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{
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std::cout << "\nA distinct unit for each type is efficient and accurate\n"
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"when adding two values of the same very big\n"
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"or very small type:\n\n";
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length::fm<float> L1A = 2._q_fm;
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length::fm<float> L2A = 3._q_fm;
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length::fm<float> LrA = L1A + L2A;
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fmt::print("{:%.30Q %q}\n + {:%.30Q %q}\n = {:%.30Q %q}\n\n",L1A,L2A,LrA);
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std::cout << "The single unit method must convert large\n"
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"or small values in other units to the base unit.\n"
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"This is both inefficient and inaccurate\n\n";
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length::m<float> L1B = L1A;
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length::m<float> L2B = L2A;
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length::m<float> LrB = L1B + L2B;
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fmt::print("{:%.30Q %q}\n + {:%.30Q %q}\n = {:%.30Q %q}\n\n",L1B,L2B,LrB);
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std::cout << "In multiplication and division:\n\n";
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area::fm2<float> ArA = L1A * L2A;
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fmt::print("{:%.30Q %q}\n * {:%.30Q %q}\n = {:%.30Q %q}\n\n",L1A,L2A,ArA);
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std::cout << "similar problems arise\n\n";
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area::m2<float> ArB = L1B * L2B;
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fmt::print("{:%.30Q %q}\n * {:%.30Q %q}\n = {:%.30Q %q}\n\n",L1B,L2B,ArB);
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}
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int main()
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{
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std::cout << "This demo was originally posted on comp.lang.c++.moderated in 2006\n";
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std::cout << "http://compgroups.net/comp.lang.c++.moderated/dimensional-analysis-units/51712\n";
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std::cout << "Here converted to use mpusz/units library.\n\n";
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simple_quantities();
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quantities_with_typed_units();
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calcs_comparison();
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}
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