forked from mpusz/mp-units
152 lines
5.5 KiB
C++
152 lines
5.5 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 <units/format.h>
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#include <units/isq/si/area.h>
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#include <units/isq/si/iau/length.h>
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#include <units/isq/si/imperial/length.h>
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#include <units/isq/si/international/length.h>
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#include <units/isq/si/length.h>
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#include <units/isq/si/time.h>
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#include <units/isq/si/typographic/length.h>
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#include <units/isq/si/us/length.h>
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#include <units/isq/si/volume.h>
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#include <units/quantity_io.h>
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#include <iostream>
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namespace {
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using namespace units;
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void simple_quantities()
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{
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using namespace units::isq::si;
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using namespace units::isq::si::international;
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using distance = length<metre>;
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using duration = isq::si::time<second>;
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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 duration sec = 1_q_s;
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constexpr duration min = 1_q_min;
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constexpr duration 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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using namespace units::isq;
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using namespace units::isq::si;
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using namespace units::isq::si::international;
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constexpr length<kilometre> km = 1.0_q_km;
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constexpr length<mile> miles = 1.0_q_mi;
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std::cout.precision(6);
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constexpr si::time<second> sec = 1_q_s;
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constexpr si::time<minute> min = 1_q_min;
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constexpr si::time<hour> 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<metre> 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 << " = " << quantity_cast<si::astronomical_unit>(meter) << '\n';
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std::cout << " = " << quantity_cast<si::iau::angstrom>(meter) << '\n';
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std::cout << " = " << quantity_cast<si::imperial::chain>(meter) << '\n';
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std::cout << " = " << quantity_cast<si::international::fathom>(meter) << '\n';
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std::cout << " = " << quantity_cast<si::us::fathom>(meter) << '\n';
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std::cout << " = " << quantity_cast<si::international::foot>(meter) << '\n';
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std::cout << " = " << quantity_cast<si::us::foot>(meter) << '\n';
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std::cout << " = " << quantity_cast<si::international::inch>(meter) << '\n';
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std::cout << " = " << quantity_cast<si::iau::light_year>(meter) << '\n';
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std::cout << " = " << quantity_cast<si::international::mile>(meter) << '\n';
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std::cout << " = " << quantity_cast<si::international::nautical_mile>(meter) << '\n';
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std::cout << " = " << quantity_cast<si::iau::parsec>(meter) << '\n';
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std::cout << " = " << quantity_cast<si::typographic::pica_comp>(meter) << '\n';
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std::cout << " = " << quantity_cast<si::typographic::pica_prn>(meter) << '\n';
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std::cout << " = " << quantity_cast<si::typographic::point_comp>(meter) << '\n';
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std::cout << " = " << quantity_cast<si::typographic::point_prn>(meter) << '\n';
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std::cout << " = " << quantity_cast<si::imperial::rod>(meter) << '\n';
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std::cout << " = " << quantity_cast<si::international::yard>(meter) << '\n';
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}
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void calcs_comparison()
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{
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using namespace units::isq::si;
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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<femtometre,float> L1A = 2._q_fm;
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length<femtometre,float> L2A = 3._q_fm;
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length<femtometre,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<metre,float> L1B = L1A;
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length<metre,float> L2B = L2A;
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length<metre,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<square_femtometre,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<square_metre,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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} // namespace
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int main()
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{
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std::cout << "This demo was originally posted on com.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 mp-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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