Fractional dimension exponents support added

test/unit_test/test_custom_units.cpp

@@ -0,0 +1,64 @@
+// The MIT License (MIT)
+//
+// Copyright (c) 2018 Mateusz Pusz
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+#include <units/dimensions/voltage.h>
+
+
+/* ************** DERIVED DIMENSIONS THAT INCLUDE UNITS WITH SPECIAL NAMES **************** */
+
+namespace {
+
+using namespace std::experimental::units;
+
+  // power spectral density
+  // todo: add support for make_dimension_t of non base units
+  //  struct power_spectral_density : make_dimension_t<exp<voltage, 2>, exp<frequency, -1>> {};
+  struct power_spectral_density
+      : make_dimension_t<exp<base_dim_mass, 2>, exp<base_dim_length, 4>, exp<base_dim_time, -6>, exp<base_dim_time, -1>> {
+  };
+  struct sq_volt_per_hertz : unit<power_spectral_density> {};
+
+  // amplitude spectral density
+  //  struct dimension_amplitude_spectral_density : make_dimension_t<exp<voltage, 1>, exp<frequency, -1, 2>> {};
+  struct amplitude_spectral_density
+      : make_dimension_t<exp<base_dim_mass, 1>, exp<base_dim_length, 2>, exp<base_dim_time, -3>, exp<base_dim_current, -1>, exp<base_dim_time, 1, 2>> {
+  };
+  // todo: add support for derived_unit
+  //struct volt_per_sq_hertz : derived_unit<amplitude_spectral_density, kilogram, metre, second, ampere > {};
+  struct volt_per_sqrt_hertz : unit<amplitude_spectral_density> {};
+}
+
+namespace std::experimental::units {
+
+template<> struct downcasting_traits<downcast_from<power_spectral_density>> : downcast_to<power_spectral_density> {};
+template<> struct downcasting_traits<downcast_from<sq_volt_per_hertz>> : downcast_to<sq_volt_per_hertz> {};
+
+template<> struct downcasting_traits<downcast_from<amplitude_spectral_density>> : downcast_to<amplitude_spectral_density> {};
+template<> struct downcasting_traits<downcast_from<volt_per_sqrt_hertz>> : downcast_to<volt_per_sqrt_hertz> {};
+
+}
+
+namespace {
+
+  //static_assert(sqrt(quantity<sq_volt_per_hertz>(4)) = quantity<volt_per_sqrt_hertz>(2));
+
+}