https://github.com/benbarsdell/rtunits

A single-header C++11 library for working with physical quantities at runtime.
https://github.com/benbarsdell/rtunits

astronomy-instrumentation conversion-library cpp-library dimensional-analysis single-header-lib units-measures-converter units-of-measure units-of-measurement

Last synced: about 1 month ago
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A single-header C++11 library for working with physical quantities at runtime.

• Host: GitHub
• URL: https://github.com/benbarsdell/rtunits
• Owner: benbarsdell
• License: bsd-3-clause
• Created: 2019-09-03T00:04:09.000Z (over 5 years ago)
• Default Branch: master
• Last Pushed: 2023-06-18T13:38:47.000Z (over 1 year ago)
• Last Synced: 2023-10-20T18:11:33.210Z (over 1 year ago)
• Topics: astronomy-instrumentation, conversion-library, cpp-library, dimensional-analysis, single-header-lib, units-measures-converter, units-of-measure, units-of-measurement
• Language: C++
• Homepage:
• Size: 66.4 KB
• Stars: 3
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# RT-Units

[![Build Status](https://github.com/benbarsdell/rtunits/actions/workflows/ci.yml/badge.svg?event=push)](https://github.com/benbarsdell/rtunits/actions?query=workflow%3ACI)

RT-Units - A single-header C++11 library for working with physical

quantities at runtime, including support for parsing and

serialization.

The `rtunits::Quantity` template represents a physical quantity with a

magnitude and dimensions. It supports an extensive set of physical

units and scale prefixes, and implements robust parsing and

serialization.

# Example

```C++

#include 

#include 

using rtunits::Quantity64;

using rtunits::SpecificQuantity64;

using Dims = rtunits::Dimensions;

int main(int argc, char* argv[]) {

  Quantity64 force(1.25, "kN");

  Quantity64 displacement(12.0, "mm");

  Quantity64 work = force * displacement + 5. * Quantity64::joule();

  std::cout << "Work: " << work << '\n';

  std::cout << "Dims: " << work.dimensions() << '\n';

  std::cout << (work.dimensions() == Dims::Force() * Dims::Length()) << '\n';

  std::cout << (work == Quantity64(20, "J")) << '\n';

  std::cout << (work.value("mW s") == 20e3) << '\n';

  SpecificQuantity64 dm(500., "pc/cm^3");

  dm *= 2;

  std::cout << "DM: " << dm << '\n';

  std::cout << "  = " << static_cast(dm) << std::endl;

}

```

Output:

```

Work: 20 m^2 kg s^-2

Dims: L^2 M T^-2

1

1

1

DM: 1000 pc/cm^3

  = 3.08568e+25 m^-2

```

# Performance

Units are parsed using a very large regular expression, which can be slow.

To improve performance, consider doing the following:

- Define RTUNITS_USE_BOOST_REGEX=1 to use [boost::regex](https://github.com/boostorg/regex),

  which is 4-8x faster than std::regex. (Note that boost::regex can be used as a

  standalone header-only library without requiring the rest of Boost).

- Define RTUNITS_NO_ASTRONOMY_UNITS=1, RTUNITS_NO_CGS_UNITS=1, and/or

  RTUNITS_NO_MISC_UNITS=1 before including `rtunits.hpp` to disable support for

  unneeded units. This can speed up parsing by up to 2x.

# Error handling

Exceptions are used by default, but can be disabled by defining

`RTUNITS_USE_EXCEPTIONS` to 0 before including the rtunits header:

```

#define RTUNITS_USE_EXCEPTIONS 0

#include 

```

# Tests

Run tests using the following commands:

    $ mkdir build

    $ cd build

    $ cmake ..

    $ make check