Updated the Coordinate System Framework (#146)

To fix the position of any astronomical object, this coordinate system framework provides tools to assign a different pair of numbers to every point in the sky.

Each system takes its name from the fundamental plane which it uses as a reference

This framework contains

Base class coord_sys

and the four Coordinate System

1. Equatorial Coordinate System equatorial_coord.hpp
2. Horizon Coordinate System horizon_coord.hpp
3. Ecliptic Coordinate System ecliptic_coord.hpp
4. Galactic Coordinate System galactic_coord.hpp

include/boost/astronomy/coordinate/coord_sys/coord_sys.hpp

@@ -0,0 +1,55 @@
+/*=============================================================================
+Copyright 2020 Syed Ali Hasan <alihasan9922@gmail.com>
+
+Distributed under the Boost Software License, Version 1.0. (See accompanying
+file License.txt or copy at https://www.boost.org/LICENSE_1_0.txt)
+=============================================================================*/
+
+#ifndef BOOST_ASTRONOMY_COORD_SYS_HPP
+#define BOOST_ASTRONOMY_COORD_SYS_HPP
+
+#include <cstddef>
+#include <type_traits>
+#include <boost/static_assert.hpp>
+#include <boost/geometry/core/cs.hpp>
+#include <boost/units/get_dimension.hpp>
+#include <boost/geometry/geometries/point.hpp>
+#include <boost/geometry/algorithms/transform.hpp>
+
+namespace boost { namespace astronomy { namespace coordinate {
+
+namespace bg = boost::geometry;
+
+typedef bg::degree degree;
+typedef bg::radian radian;
+
+template
+<
+    std::size_t DimensionCount,
+    typename CoordinateSystem,
+    typename CoordinateType=double
+>
+struct coord_sys
+{
+  ///@cond INTERNAL
+  BOOST_STATIC_ASSERT_MSG((DimensionCount == 2),
+                          "DimensionCount is expected to be 2");
+  BOOST_STATIC_ASSERT_MSG((std::is_arithmetic<CoordinateType>::value),
+                          "Coordinate Type must be an arithmetic type");
+  ///@endcond
+protected:
+    bg::model::point<CoordinateType, DimensionCount, CoordinateSystem> point;
+
+public:
+    typedef CoordinateSystem system;
+    typedef CoordinateType type;
+
+    bg::model::point<CoordinateType, DimensionCount, CoordinateSystem> get_point() const
+    {
+        return this->point;
+    }
+}; //coord_sys
+
+}}}
+
+#endif //BOOST_ASTRONOMY_COORD_SYS_HPP

include/boost/astronomy/coordinate/coord_sys/ecliptic_coord.hpp

@@ -0,0 +1,192 @@
+/*=============================================================================
+Copyright 2020 Syed Ali Hasan <alihasan9922@gmail.com>
+
+Distributed under the Boost Software License, Version 1.0. (See accompanying
+file License.txt or copy at https://www.boost.org/LICENSE_1_0.txt)
+=============================================================================*/
+
+#ifndef BOOST_ASTRONOMY_ECLIPTIC_COORD_HPP
+#define BOOST_ASTRONOMY_ECLIPTIC_COORD_HPP
+
+#include <iostream>
+#include <boost/static_assert.hpp>
+#include <boost/geometry/core/cs.hpp>
+#include <boost/units/get_dimension.hpp>
+#include <boost/geometry/geometries/point.hpp>
+#include <boost/units/systems/si/plane_angle.hpp>
+#include <boost/units/systems/si/dimensionless.hpp>
+#include <boost/units/physical_dimensions/plane_angle.hpp>
+#include <boost/astronomy/coordinate/coord_sys/coord_sys.hpp>
+
+/**
+ * The plane containing the Earth’s orbit around the Sun is called
+ * the ecliptic and the other planets in our Solar System also move
+ * in orbits close to this plane.
+ *
+ * When making calculations on objects in the Solar System it is
+ * therefore often convenient to define positions with respect to
+ * the ecliptic, that is, to use the ecliptic coordinate system.
+ *
+ * Ecliptic Latitude
+ * The ecliptic plane is extended until it intersects the celestial
+ * sphere to create an “ecliptic equator” as the reference point from
+ * which Ecliptic Latitudes are measured. The Ecliptic Latitude, denoted
+ * by β, is the angular distance that an object P lies above or below the
+ * ecliptic plane and falls within the range ±90◦.
+ * Latitudes above the ecliptic plane are positive angles while latitudes
+ * below the ecliptic plane are negative angles. An object, such as the Sun,
+ * whose orbit lies entirely within the ecliptic plane has an ecliptic latitude
+ * of 0◦.
+ *
+ * Ecliptic Longitude
+ * The Ecliptic Longitude, designated by λ, measures how far away an object is
+ * from the First Point of Aries. The Ecliptic Longitude is in the range [0◦, 360◦]
+ * and measured along the ecliptic toward the First Point of Aries.
+ */
+
+namespace boost { namespace astronomy { namespace coordinate {
+
+namespace bu = boost::units;
+namespace bg = boost::geometry;
+
+template
+<
+    typename CoordinateType = double,
+    typename LatQuantity = bu::quantity<bu::si::plane_angle, CoordinateType>,
+    typename LonQuantity = bu::quantity<bu::si::plane_angle, CoordinateType>
+>
+struct ecliptic_coord : public coord_sys
+    <2, bg::cs::spherical<bg::radian>, CoordinateType>
+{
+  ///@cond INTERNAL
+  BOOST_STATIC_ASSERT_MSG(
+      ((std::is_same<typename bu::get_dimension<LatQuantity>::type,
+          bu::plane_angle_dimension>::value) &&
+       (std::is_same<typename bu::get_dimension<LonQuantity>::type,
+           bu::plane_angle_dimension>::value)),
+      "Latitude and Longitude must be of plane angle type");
+  BOOST_STATIC_ASSERT_MSG((std::is_floating_point<CoordinateType>::value),
+                          "CoordinateType must be a floating-point type");
+  ///@endcond
+public:
+    typedef LatQuantity quantity1;
+    typedef LonQuantity quantity2;
+
+    //Default constructor
+    ecliptic_coord() {}
+
+    ecliptic_coord
+    (
+            LatQuantity const &Lat,
+            LonQuantity const &Lon
+    )
+    {
+        this->set_lat_lon(Lat, Lon);
+    }
+
+    //Create a tuple of Ecliptic Latitude and Ecliptic Longitude
+    std::tuple<LatQuantity, LonQuantity> get_lat_lon() const
+    {
+        return std::make_tuple(this->get_lat(), this->get_lon());
+    }
+
+    //Get Ecliptic Latitude
+    LatQuantity get_lat() const
+    {
+        return static_cast<LatQuantity>
+        (
+            bu::quantity<bu::si::plane_angle, CoordinateType>::from_value
+                    (bg::get<0>(this->point))
+        );
+    }
+
+    //Get Ecliptic Longitude
+    LonQuantity get_lon() const
+    {
+        return static_cast<LonQuantity>
+        (
+                bu::quantity<bu::si::plane_angle, CoordinateType>::from_value
+                        (bg::get<1>(this->point))
+        );
+    }
+
+    //Set value of Ecliptic Latitude and Ecliptic Longitude
+    void set_lat_lon
+    (
+            LatQuantity const &Lat,
+            LonQuantity const &Lon
+    )
+    {
+        this->set_lat(Lat);
+        this->set_lon(Lon);
+    }
+
+    //Set Ecliptic Latitude
+    void set_lat(LatQuantity const &Lat)
+    {
+        bg::set<0>
+            (
+                this->point,
+                static_cast<bu::quantity<bu::si::plane_angle, CoordinateType>>(Lat).value()
+            );
+    }
+
+    //Set Ecliptic Longitude
+    void set_lon(LonQuantity const &Lon)
+    {
+        bg::set<1>
+            (
+                this->point,
+                static_cast<bu::quantity<bu::si::plane_angle, CoordinateType>>(Lon).value()
+            );
+    }
+
+}; //ecliptic_coord
+
+//Make Ecliptic Coordinate
+template
+<
+    typename CoordinateType,
+    template<typename Unit2, typename CoordinateType_> class LatQuantity,
+    template<typename Unit1, typename CoordinateType_> class LonQuantity,
+    typename Unit1,
+    typename Unit2
+>
+ecliptic_coord
+<
+    CoordinateType,
+    LatQuantity<Unit2, CoordinateType>,
+    LonQuantity<Unit1, CoordinateType>
+> make_ecliptic_coord
+(
+    LatQuantity<Unit2, CoordinateType> const &Lat,
+    LonQuantity<Unit1, CoordinateType> const &Lon
+)
+{
+    return ecliptic_coord
+        <
+            CoordinateType,
+            LatQuantity<Unit2, CoordinateType>,
+            LonQuantity<Unit1, CoordinateType>
+        > (Lat, Lon);
+}
+
+//Print Ecliptic Coordinates
+template
+<
+    typename CoordinateType,
+    class LatQuantity,
+    class LonQuantity
+>
+std::ostream &operator << (std::ostream &out, ecliptic_coord
+        <CoordinateType, LatQuantity, LonQuantity> const &point) {
+    out << "Ecliptic Coordinate (Ecliptic Latitude: "
+        << point.get_lat() << ", Ecliptic Longitude: "
+        << point.get_lon() << ")";
+
+    return out;
+}
+
+}}}
+
+#endif //BOOST_ASTRONOMY_ECLIPTIC_COORD_HPP