Mu

Mu is C++ header-only library for working with physical units.

This library lets you define quantity objects that are strongly typed by their phsical units. Quantity objects can be added, subtracted, negated, multiplied, or divided while adhering to the rules of dimensional analysis.

Quantity objects contain a value that stores the magnitude of the quantity. The value can be any fundamental C++ type, and the library provides customization points allowing clients to integrate their own types.

Quantity types are templated on a units type. The template parameters determine the dimensions and scale of the quantity. It is a compile-time error to assign quantities of different dimensions, and if the dimensions are the same, the library determines the correct scale factor at compile-time. Users can define their own units, which can be fundamental or composed from existing units.

Example:

#include <mu/mu.hpp>
#include <sstream>

int main() {
    // Calculate speed in km/h.
    mu::quantity<int, mu::kilometer> distance{100};
    mu::quantity<int, mu::hour> time{5};
    auto speed_kmph = distance / time;

    // Converts km/h to m/s.
    mu::quantity<double, mu::meter_per_second> speed_mps = speed_kmph;

    // Print both quantities.
    std::ostringstream sout;
    sout << mu::stream::symbols
         << mu::stream::superscript_exponents
         << mu::stream::mult_sep(" • ")
         << speed_kmph << " = "
         << speed_mps;

    // Check expected string.
    std::string actual = sout.str();
    std::string expected = "20 km • hr⁻¹ = 5.55556 m • s⁻¹";
    return actual != expected;
}

Prior Art

This library is a hobby project (and I learned a lot while making it)! I currently do not recommend using this library in production, because there already exist other mature libraries for the same purpose. You might consider using:

1. mpusz/mp-units
2. aurora-opensource/Au