.NET wrapper for GeographicLib::Rhumb. More...

#include <Rhumb.h>

Public Types
enum	mask { mask::NONE, mask::LATITUDE, mask::LONGITUDE, mask::AZIMUTH, mask::DISTANCE, mask::AREA, mask::LONG_UNROLL, mask::ALL }

Public Member Functions
void	Direct (double lat1, double lon1, double azi12, double s12, [System::Runtime::InteropServices::Out] double% lat2, [System::Runtime::InteropServices::Out] double% lon2)

void	Direct (double lat1, double lon1, double azi12, double s12, [System::Runtime::InteropServices::Out] double% lat2, [System::Runtime::InteropServices::Out] double% lon2, [System::Runtime::InteropServices::Out] double% S12)

void	GenDirect (double lat1, double lon1, double azi12, double s12, Rhumb::mask outmask, [System::Runtime::InteropServices::Out] double% lat2, [System::Runtime::InteropServices::Out] double% lon2, [System::Runtime::InteropServices::Out] double% S12)

void	GenInverse (double lat1, double lon1, double lat2, double lon2, Rhumb::mask outmask, [System::Runtime::InteropServices::Out] double% s12, [System::Runtime::InteropServices::Out] double% azi12, [System::Runtime::InteropServices::Out] double% S12)

void	Inverse (double lat1, double lon1, double lat2, double lon2, [System::Runtime::InteropServices::Out] double% s12, [System::Runtime::InteropServices::Out] double% azi12)

void	Inverse (double lat1, double lon1, double lat2, double lon2, [System::Runtime::InteropServices::Out] double% s12, [System::Runtime::InteropServices::Out] double% azi12, [System::Runtime::InteropServices::Out] double% S12)

RhumbLine	Line (double lat1, double lon1, double azi12)

	Rhumb (double a, double f, bool exact)

	~Rhumb ()
	The destructor calls the finalizer. More...

Private Member Functions
	!Rhumb (void)

Private Attributes
GeographicLib::Rhumb *	m_pRhumb

Inspector functions.
property double	MajorRadius { double get()

property double	Flattening { double get()

property double	EllipsoidArea { double get()

System::IntPtr	GetUnmanaged ()

static Rhumb	WGS84 ()

Detailed Description

.NET wrapper for GeographicLib::Rhumb.

This class allows .NET applications to access GeographicLib::Rhumb.

Solve of the direct and inverse rhumb problems.

The path of constant azimuth between two points on a ellipsoid at (lat1, lon1) and (lat2, lon2) is called the rhumb line (also called the loxodrome). Its length is s12 and its azimuth is azi12. (The azimuth is the heading measured clockwise from north.)

Given lat1, lon1, azi12, and s12, we can determine lat2, and lon2. This is the direct rhumb problem and its solution is given by the function Rhumb::Direct.

Given lat1, lon1, lat2, and lon2, we can determine azi12 and s12. This is the inverse rhumb problem, whose solution is given by Rhumb::Inverse. This finds the shortest such rhumb line, i.e., the one that wraps no more than half way around the earth. If the end points are on opposite meridians, there are two shortest rhumb lines and the east-going one is chosen.

These routines also optionally calculate the area under the rhumb line, S12. This is the area, measured counter-clockwise, of the rhumb line quadrilateral with corners (lat1,lon1), (0,lon1), (0,lon2), and (lat2,lon2).

Note that rhumb lines may be appreciably longer (up to 50%) than the corresponding Geodesic. For example the distance between London Heathrow and Tokyo Narita via the rhumb line is 11400 km which is 18% longer than the geodesic distance 9600 km.

For more information on rhumb lines see rhumb.

C# Example:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using NETGeographicLib;
 
namespace example_Rhumb
{
    class Program
    {
        static void Main(string[] args)
        {
            try {
            Rhumb rhumb = new Rhumb(Constants.WGS84.MajorRadius, Constants.WGS84.Flattening, true);
            // Alternatively: const Rhumb& rhumb = Rhumb::WGS84();
            {
                // Sample direct calculation, travelling about NE from JFK
                double lat1 = 40.6, lon1 = -73.8, s12 = 5.5e6, azi12 = 51;
                double lat2, lon2;
                rhumb.Direct(lat1, lon1, azi12, s12, out lat2, out lon2);
                    Console.WriteLine( "{0} {1}", lat2, lon2 );
            }
            {
                // Sample inverse calculation, JFK to LHR
                double
                lat1 = 40.6, lon1 = -73.8, // JFK Airport
                lat2 = 51.6, lon2 = -0.5;  // LHR Airport
                double s12, azi12;
                rhumb.Inverse(lat1, lon1, lat2, lon2, out s12, out azi12);
                    Console.WriteLine( "{0} {1}", s12, azi12 );
            }
            }
            catch (GeographicErr e) {
                Console.WriteLine(String.Format("Caught exception: {0}", e.Message));
            }
        }
    }
}

Managed C++ Example:

// Example of using the GeographicLib::Rhumb class
 
#include <iostream>
#include <exception>
#include <GeographicLib/Rhumb.hpp>
#include <GeographicLib/Constants.hpp>
 
using namespace std;
using namespace GeographicLib;
 
int main() {
  try {
    Rhumb rhumb(Constants::WGS84_a(), Constants::WGS84_f());
    // Alternatively: const Rhumb& rhumb = Rhumb::WGS84();
    {
      // Sample direct calculation, travelling about NE from JFK
      double lat1 = 40.6, lon1 = -73.8, s12 = 5.5e6, azi12 = 51;
      double lat2, lon2;
      rhumb.Direct(lat1, lon1, azi12, s12, lat2, lon2);
      cout << lat2 << " " << lon2 << "\n";
    }
    {
      // Sample inverse calculation, JFK to LHR
      double
        lat1 = 40.6, lon1 = -73.8, // JFK Airport
        lat2 = 51.6, lon2 = -0.5;  // LHR Airport
      double s12, azi12;
      rhumb.Inverse(lat1, lon1, lat2, lon2, s12, azi12);
      cout << s12 << " " << azi12 << "\n";
    }
  }
  catch (const exception& e) {
    cerr << "Caught exception: " << e.what() << "\n";
    return 1;
  }
}

Visual Basic Example:

Imports NETGeographicLib
 
Module example_Rhumb
    Sub Main()
        Try
            Dim rhumb As Rhumb = New Rhumb(Constants.WGS84.MajorRadius, Constants.WGS84.Flattening, True)
            ' Alternatively: const Rhumb& rhumb = Rhumb::WGS84();
 
            ' Sample direct calculation, travelling about NE from JFK
            Dim lat1 As Double = 40.6, lon1 = -73.8, s12 = 5500000.0, azi12 = 51
            Dim lat2 As Double, lon2
            rhumb.Direct(lat1, lon1, azi12, s12, lat2, lon2)
            Console.WriteLine("{0} {1}", lat2, lon2)
 
            ' Sample inverse calculation, JFK to LHR
            lat1 = 40.6 : lon1 = -73.8 ' JFK Airport
            lat2 = 51.6 : lon2 = -0.5  ' LHR Airport
            rhumb.Inverse(lat1, lon1, lat2, lon2, s12, azi12)
            Console.WriteLine("{0} {1}", s12, azi12)
        Catch ex As GeographicErr
            Console.WriteLine(String.Format("Caught exception: {0}", ex.Message))
        End Try
    End Sub
End Module

INTERFACE DIFFERENCES:
The MajorRadius and Flattening functions are implemented as properties.

Definition at line 65 of file Rhumb.h.

Member Enumeration Documentation

◆ mask

enum NETGeographicLib::Rhumb::mask

strong

Bit masks for what calculations to do. They specify which results to return in the general routines Rhumb::GenDirect and Rhumb::GenInverse routines. RhumbLine::mask is a duplication of this enum.

Enumerator
NONE	No output.
LATITUDE	Calculate latitude lat2.
LONGITUDE	Calculate longitude lon2.
AZIMUTH	Calculate azimuth azi12.
DISTANCE	Calculate distance s12.
AREA	Calculate area S12.
LONG_UNROLL	Unroll lon2 in the direct calculation.
ALL	Calculate everything. (LONG_UNROLL is not included in this mask.)

Definition at line 78 of file Rhumb.h.

Constructor & Destructor Documentation

◆ !Rhumb()

Rhumb::!Rhumb ( void )

private

Definition at line 19 of file dotnet/NETGeographicLib/Rhumb.cpp.

◆ Rhumb()

Rhumb::Rhumb	(	double	a,
		double	f,
		bool	exact
	)

Constructor for a ellipsoid with

Parameters

[in]	a	equatorial radius (meters).
[in]	f	flattening of ellipsoid. Setting f = 0 gives a sphere. Negative f gives a prolate ellipsoid.
[in]	exact	if true (the default) use an addition theorem for elliptic integrals to compute divided differences; otherwise use series expansion (accurate for \|f\| < 0.01).

Exceptions

GeographicErr if a or (1 − f) a is not positive.

See rhumb, for a detailed description of the exact parameter.

Definition at line 29 of file dotnet/NETGeographicLib/Rhumb.cpp.

◆ ~Rhumb()

NETGeographicLib::Rhumb::~Rhumb ( )

inline

The destructor calls the finalizer.

Definition at line 140 of file Rhumb.h.

Member Function Documentation

◆ Direct() [1/2]

void Rhumb::Direct	(	double	lat1,
		double	lon1,
		double	azi12,
		double	s12,
		[System::Runtime::InteropServices::Out] double%	lat2,
		[System::Runtime::InteropServices::Out] double%	lon2
	)

Solve the direct rhumb problem without the area.

Parameters

[in]	lat1	latitude of point 1 (degrees).
[in]	lon1	longitude of point 1 (degrees).
[in]	azi12	azimuth of the rhumb line (degrees).
[in]	s12	distance between point 1 and point 2 (meters); it can be negative.
[out]	lat2	latitude of point 2 (degrees).
[out]	lon2	longitude of point 2 (degrees).

lat1 should be in the range [−90°, 90°]. The values of lon2 and azi2 returned are in the range [−180°, 180°).

If point 1 is a pole, the cosine of its latitude is taken to be 1/ε² (where ε is 2^-52). This position, which is extremely close to the actual pole, allows the calculation to be carried out in finite terms. If s12 is large enough that the rhumb line crosses a pole, the longitude of point 2 is indeterminate (a NaN is returned for lon2).

Definition at line 59 of file dotnet/NETGeographicLib/Rhumb.cpp.

◆ Direct() [2/2]

void Rhumb::Direct	(	double	lat1,
		double	lon1,
		double	azi12,
		double	s12,
		[System::Runtime::InteropServices::Out] double%	lat2,
		[System::Runtime::InteropServices::Out] double%	lon2,
		[System::Runtime::InteropServices::Out] double%	S12
	)

Solve the direct rhumb problem returning also the area.

Parameters

[in]	lat1	latitude of point 1 (degrees).
[in]	lon1	longitude of point 1 (degrees).
[in]	azi12	azimuth of the rhumb line (degrees).
[in]	s12	distance between point 1 and point 2 (meters); it can be negative.
[out]	lat2	latitude of point 2 (degrees).
[out]	lon2	longitude of point 2 (degrees).
[out]	S12	area under the rhumb line (meters²).

lat1 should be in the range [−90°, 90°]. The value of lon2 returned is in the range [−180°, 180°).

If point 1 is a pole, the cosine of its latitude is taken to be 1/ε² (where ε is 2^-52). This position, which is extremely close to the actual pole, allows the calculation to be carried out in finite terms. If s12 is large enough that the rhumb line crosses a pole, the longitude of point 2 is indeterminate (a NaN is returned for lon2 and S12).

Definition at line 46 of file dotnet/NETGeographicLib/Rhumb.cpp.

◆ GenDirect()

void Rhumb::GenDirect	(	double	lat1,
		double	lon1,
		double	azi12,
		double	s12,
		Rhumb::mask	outmask,
		[System::Runtime::InteropServices::Out] double%	lat2,
		[System::Runtime::InteropServices::Out] double%	lon2,
		[System::Runtime::InteropServices::Out] double%	S12
	)

The general direct rhumb problem. Rhumb::Direct is defined in terms of this function.

Parameters

[in]	lat1	latitude of point 1 (degrees).
[in]	lon1	longitude of point 1 (degrees).
[in]	azi12	azimuth of the rhumb line (degrees).
[in]	s12	distance between point 1 and point 2 (meters); it can be negative.
[in]	outmask	a bitor'ed combination of Rhumb::mask values specifying which of the following parameters should be set.
[out]	lat2	latitude of point 2 (degrees).
[out]	lon2	longitude of point 2 (degrees).
[out]	S12	area under the rhumb line (meters²).

The Rhumb::mask values possible for outmask are

outmask |= Rhumb.LATITUDE for the latitude lat2;
outmask |= Rhumb.LONGITUDE for the latitude lon2;
outmask |= Rhumb.AREA for the area S12;
outmask |= Rhumb:.ALL for all of the above;
outmask |= Rhumb.LONG_UNROLL to unroll lon2 instead of wrapping it into the range [−180°, 180°).

With the LONG_UNROLL bit set, the quantity lon2 − lon1 indicates how many times the rhumb line wrapped around the ellipsoid.

Definition at line 70 of file dotnet/NETGeographicLib/Rhumb.cpp.

◆ GenInverse()

void Rhumb::GenInverse	(	double	lat1,
		double	lon1,
		double	lat2,
		double	lon2,
		Rhumb::mask	outmask,
		[System::Runtime::InteropServices::Out] double%	s12,
		[System::Runtime::InteropServices::Out] double%	azi12,
		[System::Runtime::InteropServices::Out] double%	S12
	)

The general inverse rhumb problem. Rhumb::Inverse is defined in terms of this function.

Parameters

[in]	lat1	latitude of point 1 (degrees).
[in]	lon1	longitude of point 1 (degrees).
[in]	lat2	latitude of point 2 (degrees).
[in]	lon2	longitude of point 2 (degrees).
[in]	outmask	a bitor'ed combination of Rhumb::mask values specifying which of the following parameters should be set.
[out]	s12	rhumb distance between point 1 and point 2 (meters).
[out]	azi12	azimuth of the rhumb line (degrees).
[out]	S12	area under the rhumb line (meters²).

The Rhumb::mask values possible for outmask are

outmask |= Rhumb::DISTANCE for the latitude s12;
outmask |= Rhumb::AZIMUTH for the latitude azi12;
outmask |= Rhumb::AREA for the area S12;
outmask |= Rhumb::ALL for all of the above;

Definition at line 109 of file dotnet/NETGeographicLib/Rhumb.cpp.

◆ GetUnmanaged()

System::IntPtr Rhumb::GetUnmanaged ( )

return The unmanaged pointer to the GeographicLib::Geodesic.

This function is for internal use only.

Definition at line 146 of file dotnet/NETGeographicLib/Rhumb.cpp.

◆ Inverse() [1/2]

void Rhumb::Inverse	(	double	lat1,
		double	lon1,
		double	lat2,
		double	lon2,
		[System::Runtime::InteropServices::Out] double%	s12,
		[System::Runtime::InteropServices::Out] double%	azi12
	)

Solve the inverse rhumb problem without the area.

Parameters

[in]	lat1	latitude of point 1 (degrees).
[in]	lon1	longitude of point 1 (degrees).
[in]	lat2	latitude of point 2 (degrees).
[in]	lon2	longitude of point 2 (degrees).
[out]	s12	rhumb distance between point 1 and point 2 (meters).
[out]	azi12	azimuth of the rhumb line (degrees).

The shortest rhumb line is found. lat1 and lat2 should be in the range [−90°, 90°]. The value of azi12 returned is in the range [−180°, 180°).

If either point is a pole, the cosine of its latitude is taken to be 1/ε² (where ε is 2^-52). This position, which is extremely close to the actual pole, allows the calculation to be carried out in finite terms.

Definition at line 98 of file dotnet/NETGeographicLib/Rhumb.cpp.

◆ Inverse() [2/2]

void Rhumb::Inverse	(	double	lat1,
		double	lon1,
		double	lat2,
		double	lon2,
		[System::Runtime::InteropServices::Out] double%	s12,
		[System::Runtime::InteropServices::Out] double%	azi12,
		[System::Runtime::InteropServices::Out] double%	S12
	)

Solve the inverse rhumb problem returning also the area.

Parameters

[in]	lat1	latitude of point 1 (degrees).
[in]	lon1	longitude of point 1 (degrees).
[in]	lat2	latitude of point 2 (degrees).
[in]	lon2	longitude of point 2 (degrees).
[out]	s12	rhumb distance between point 1 and point 2 (meters).
[out]	azi12	azimuth of the rhumb line (degrees).
[out]	S12	area under the rhumb line (meters²).

The shortest rhumb line is found. If the end points are on opposite meridians, there are two shortest rhumb lines and the east-going one is chosen. lat1 and lat2 should be in the range [−90°, 90°]. The value of azi12 returned is in the range [−180°, 180°).

If either point is a pole, the cosine of its latitude is taken to be 1/ε² (where ε is 2^-52). This position, which is extremely close to the actual pole, allows the calculation to be carried out in finite terms.

Definition at line 85 of file dotnet/NETGeographicLib/Rhumb.cpp.

◆ Line()

RhumbLine Rhumb::Line	(	double	lat1,
		double	lon1,
		double	azi12
	)

Set up to compute several points on a single rhumb line.

Parameters

[in]	lat1	latitude of point 1 (degrees).
[in]	lon1	longitude of point 1 (degrees).
[in]	azi12	azimuth of the rhumb line (degrees).

Returns: a RhumbLine object.

lat1 should be in the range [−90°, 90°].

If point 1 is a pole, the cosine of its latitude is taken to be 1/ε² (where ε is 2^-52). This position, which is extremely close to the actual pole, allows the calculation to be carried out in finite terms.

Definition at line 124 of file dotnet/NETGeographicLib/Rhumb.cpp.

◆ WGS84()

Rhumb Rhumb::WGS84 ( )

static

A global instantiation of Rhumb with the parameters for the WGS84 ellipsoid.

Definition at line 139 of file dotnet/NETGeographicLib/Rhumb.cpp.

Member Data Documentation

◆ EllipsoidArea

property double NETGeographicLib::Rhumb::EllipsoidArea { double get()

Returns: the area of the ellipsoid.

Definition at line 339 of file Rhumb.h.

◆ Flattening

property double NETGeographicLib::Rhumb::Flattening { double get()

Returns: f the flattening of the ellipsoid. This is the value used in the constructor.

Definition at line 334 of file Rhumb.h.

◆ m_pRhumb

GeographicLib::Rhumb* NETGeographicLib::Rhumb::m_pRhumb

private

Definition at line 68 of file Rhumb.h.

◆ MajorRadius

property double NETGeographicLib::Rhumb::MajorRadius { double get()

Returns: the equatorial radius of the ellipsoid (meters). This is the value used in the constructor.

Definition at line 328 of file Rhumb.h.

The documentation for this class was generated from the following files:

Public Types

Public Member Functions

Private Member Functions

Private Attributes

Inspector functions.

Detailed Description

Member Enumeration Documentation

◆ mask

Constructor & Destructor Documentation

◆ !Rhumb()

◆ Rhumb()

◆ ~Rhumb()

Member Function Documentation

◆ Direct() [1/2]

◆ Direct() [2/2]

◆ GenDirect()

◆ GenInverse()

◆ GetUnmanaged()

◆ Inverse() [1/2]

◆ Inverse() [2/2]

◆ Line()

◆ WGS84()

Member Data Documentation

◆ EllipsoidArea

◆ Flattening

◆ m_pRhumb

◆ MajorRadius