Merge pull request #544 from nebkat/patch-1

feat: `ppm` parts per million
mpusz · Jan 20, 2024 · 6e8a21a · 6e8a21a
2 parents 1df2cc7 + a62f061
commit 6e8a21a
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diff --git a/docs/users_guide/framework_basics/dimensionless_quantities.md b/docs/users_guide/framework_basics/dimensionless_quantities.md
@@ -160,6 +160,8 @@ with dimensionless quantities:
 ```cpp
 inline constexpr struct percent : named_unit<"%", mag<ratio{1, 100}> * one> {} percent;
 inline constexpr struct per_mille : named_unit<basic_symbol_text{"‰", "%o"}, mag<ratio(1, 1000)> * one> {} per_mille;
+inline constexpr struct parts_per_million : named_unit<"ppm", mag<ratio(1, 1'000'000)> * one> {} parts_per_million;
+inline constexpr auto ppm = parts_per_million;
 ```
 
 

diff --git a/src/core/include/mp-units/unit.h b/src/core/include/mp-units/unit.h
@@ -605,6 +605,8 @@ template<std::intmax_t Num, std::intmax_t Den = 1, Unit U>
 // clang-format off
 inline constexpr struct percent : named_unit<"%", mag<ratio{1, 100}> * one> {} percent;
 inline constexpr struct per_mille : named_unit<basic_symbol_text{"‰", "%o"}, mag<ratio(1, 1000)> * one> {} per_mille;
+inline constexpr struct parts_per_million : named_unit<"ppm", mag<ratio(1, 1'000'000)> * one> {} parts_per_million;
+inline constexpr auto ppm = parts_per_million;
 // clang-format on
 
 

diff --git a/test/static/unit_symbol_test.cpp b/test/static/unit_symbol_test.cpp
@@ -120,6 +120,7 @@ static_assert(unit_symbol(one) == "");
 static_assert(unit_symbol(percent) == "%");
 static_assert(unit_symbol(per_mille) == "‰");
 static_assert(unit_symbol<unit_symbol_formatting{.encoding = ascii}>(per_mille) == "%o");
+static_assert(unit_symbol(parts_per_million) == "ppm");
 static_assert(unit_symbol(square(metre)) == "m²");
 static_assert(unit_symbol<unit_symbol_formatting{.encoding = ascii}>(square(metre)) == "m^2");
 static_assert(unit_symbol(cubic(metre)) == "m³");