feat: absolute_zero and ice_point point origins added to SI

src/systems/si/include/mp-units/systems/si/point_origins.h

@@ -0,0 +1,35 @@
+// 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.
+
+#pragma once
+
+#include <mp-units/quantity_point.h>
+#include <mp-units/systems/si/units.h>
+
+namespace mp_units::si {
+
+// clang-format off
+inline constexpr struct absolute_zero : absolute_point_origin<isq::thermodynamic_temperature> {} absolute_zero;
+inline constexpr struct ice_point : relative_point_origin<absolute_zero + 273.15 * kelvin> {} ice_point;
+// clang-format on
+
+}  // namespace mp_units::si

src/systems/si/include/mp-units/systems/si/si.h

@@ -23,6 +23,7 @@
 #pragma once
 
 #include <mp-units/systems/si/constants.h>
+#include <mp-units/systems/si/point_origins.h>
 #include <mp-units/systems/si/prefixes.h>
 #include <mp-units/systems/si/unit_symbols.h>
 #include <mp-units/systems/si/units.h>