mp_units::get_relative_standard_uncertainty

Returns the relative standard uncertainty of a measured constant

Synopsis

Declared in <mp-units/framework/unit_definitions.h>

template<MeasuredConstant U>
[[nodiscard]] consteval UnitMagnitude auto get_relative_standard_uncertainty(U u);

Description

For a constant declared with standard_uncertainty, the result is derived as the exact ratio of the uncertainty's canonical magnitude to the constant's one (u_r = u(x)/|x|, so the result never carries a sign even for a negative-valued constant).

There is no valid result for constants that are exact by definition. Asking for one would conflate "exact by definition" with "measured infinitely precisely", so it is a compile-time error rather than a zero magnitude.

Return Value

the relative standard uncertainty of a measured constant

Note

The return value should not be discarded.