NETGeographicLib::MagneticModel Class Reference

.NET wrapper for GeographicLib::MagneticModel. More...

#include <MagneticModel.h>

Public Member Functions
	~MagneticModel ()
Setting up the magnetic model
	MagneticModel (System::String^name, System::String^path, Geocentric^earth)
	MagneticModel (System::String^name, System::String^path)

Static Public Member Functions
static System::String	DefaultMagneticName ()
static System::String	DefaultMagneticPath ()

Public Attributes
Inspector functions
property System::String	Description { System::String^ get()
property System::String	DateTime { System::String^ get()
property System::String	MagneticFile { System::String^ get()
property System::String	MagneticModelName { System::String^ get()
property System::String	MagneticModelDirectory { System::String^ get()
property double	MinHeight { double get()
property double	MaxHeight { double get()
property double	MinTime { double get()
property double	MaxTime { double get()
property double	MajorRadius { double get()
property double	Flattening { double get()

Private Member Functions
	!MagneticModel (void)

Private Attributes
const GeographicLib::MagneticModel *	m_pMagneticModel

Compute the magnetic field
void	Field (double t, double lat, double lon, double h, [System::Runtime::InteropServices::Out] double%Bx, [System::Runtime::InteropServices::Out] double%By, [System::Runtime::InteropServices::Out] double%Bz)
void	Field (double t, double lat, double lon, double h, [System::Runtime::InteropServices::Out] double%Bx, [System::Runtime::InteropServices::Out] double%By, [System::Runtime::InteropServices::Out] double%Bz, [System::Runtime::InteropServices::Out] double%Bxt, [System::Runtime::InteropServices::Out] double%Byt, [System::Runtime::InteropServices::Out] double%Bzt)
MagneticCircle	Circle (double t, double lat, double h)
static void	FieldComponents (double Bx, double By, double Bz, [System::Runtime::InteropServices::Out] double%H, [System::Runtime::InteropServices::Out] double%F, [System::Runtime::InteropServices::Out] double%D, [System::Runtime::InteropServices::Out] double%I)
static void	FieldComponents (double Bx, double By, double Bz, double Bxt, double Byt, double Bzt, [System::Runtime::InteropServices::Out] double%H, [System::Runtime::InteropServices::Out] double%F, [System::Runtime::InteropServices::Out] double%D, [System::Runtime::InteropServices::Out] double%I, [System::Runtime::InteropServices::Out] double%Ht, [System::Runtime::InteropServices::Out] double%Ft, [System::Runtime::InteropServices::Out] double%Dt, [System::Runtime::InteropServices::Out] double%It)

Detailed Description

.NET wrapper for GeographicLib::MagneticModel.

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

Evaluate the earth's magnetic field according to a model. At present only internal magnetic fields are handled. These are due to the earth's code and crust; these vary slowly (over many years). Excluded are the effects of currents in the ionosphere and magnetosphere which have daily and annual variations.

See magnetic for details of how to install the magnetic model and the data format.

See

• General information:
  • http://geomag.org/models/index.html
• WMM2010:
  • http://ngdc.noaa.gov/geomag/WMM/DoDWMM.shtml
  • http://ngdc.noaa.gov/geomag/WMM/data/WMM2010/WMM2010COF.zip
• WMM2015:
  • http://ngdc.noaa.gov/geomag/WMM/DoDWMM.shtml
  • http://ngdc.noaa.gov/geomag/WMM/data/WMM2015/WMM2015COF.zip
• IGRF11:
  • http://ngdc.noaa.gov/IAGA/vmod/igrf.html
  • http://ngdc.noaa.gov/IAGA/vmod/igrf11coeffs.txt
  • http://ngdc.noaa.gov/IAGA/vmod/geomag70_linux.tar.gz
• EMM2010:
  • http://ngdc.noaa.gov/geomag/EMM/index.html
  • http://ngdc.noaa.gov/geomag/EMM/data/geomag/EMM2010_Sph_Windows_Linux.zip

C# Example:

using System;
using NETGeographicLib;

namespace example_MagneticModel
{
    class Program
    {
        static void Main(string[] args)
        {
            try {
                MagneticModel mag = new MagneticModel("wmm2010","");
                double lat = 27.99, lon = 86.93, h = 8820, t = 2012; // Mt Everest
                double Bx, By, Bz;
                mag.Field(t, lat,lon, h, out Bx, out By, out Bz);
                double H, F, D, I;
                MagneticModel.FieldComponents(Bx, By, Bz, out H, out F, out D, out I);
                Console.WriteLine(String.Format("{0} {1} {2} {3}", H, F, D, I));
            }
            catch (GeographicErr e) {
                Console.WriteLine(String.Format("Caught exception: {0}", e.Message));
            }
        }
    }
}

Managed C++ Example:

// Example of using the GeographicLib::MagneticModel class

#include <iostream>
#include <exception>
#include <GeographicLib/MagneticModel.hpp>

using namespace std;
using namespace GeographicLib;

int main() {
  try {
    MagneticModel mag("wmm2010");
    double lat = 27.99, lon = 86.93, h = 8820, t = 2012; // Mt Everest
    double Bx, By, Bz;
    mag(t, lat,lon, h, Bx, By, Bz);
    double H, F, D, I;
    MagneticModel::FieldComponents(Bx, By, Bz, H, F, D, I);
    cout << H << " " << F << " " << D << " " << I << "\n";
  }
  catch (const exception& e) {
    cerr << "Caught exception: " << e.what() << "\n";
    return 1;
  }
}

Visual Basic Example:

Imports NETGeographicLib

Module example_MagneticModel
    Sub Main()
        Try
            Dim mag As MagneticModel = New MagneticModel("wmm2010", "")
            Dim lat As Double = 27.99, lon = 86.93, h = 8820, t = 2012 ' Mt Everest
            Dim Bx, By, Bz As Double
            mag.Field(t, lat, lon, H, Bx, By, Bz)
            Dim bigH, F, D, I As Double
            MagneticModel.FieldComponents(Bx, By, Bz, bigH, F, D, I)
            Console.WriteLine(String.Format("{0} {1} {2} {3}", bigH, F, D, I))
        Catch ex As GeographicErr
            Console.WriteLine(String.Format("Caught exception: {0}", ex.Message))
        End Try
    End Sub
End Module

INTERFACE DIFFERENCES:
The () operator has been replaced with Field.

The following functions are implemented as properties: Description, DateTime, MagneticFile, MagneticModelName, MagneticModelDirectory, MinHeight, MaxHeight, MinTime, MaxTime, MajorRadius, and Flattening.

Definition at line 63 of file MagneticModel.h.

Constructor & Destructor Documentation

MagneticModel::!MagneticModel ( void  )

private

Definition at line 24 of file dotnet/NETGeographicLib/MagneticModel.cpp.

MagneticModel::MagneticModel	(	System::String^	name,
		System::String^	path,
		Geocentric^	earth
	)

Construct a magnetic model.

Parameters

[in]	name	the name of the model.
[in]	path	(optional) directory for data file.
[in]	earth	(optional) Geocentric object for converting coordinates.

Exceptions

GeographicErr	if the data file cannot be found, is unreadable, or is corrupt.
std::bad_alloc	if the memory necessary for storing the model can't be allocated.

A filename is formed by appending ".wmm" (World Magnetic Model) to the name. If path is specified (and is non-empty), then the file is loaded from directory, path. Otherwise the path is given by the DefaultMagneticPath().

This file contains the metadata which specifies the properties of the model. The coefficients for the spherical harmonic sums are obtained from a file obtained by appending ".cof" to metadata file (so the filename ends in ".wwm.cof").

The model is not tied to a particular ellipsoidal model of the earth. The final earth argument to the constructor specifies an ellipsoid to allow geodetic coordinates to the transformed into the spherical coordinates used in the spherical harmonic sum.

Definition at line 34 of file dotnet/NETGeographicLib/MagneticModel.cpp.

MagneticModel::MagneticModel	(	System::String^	name,
		System::String^	path
	)

Construct a magnetic model that assumes the WGS84 ellipsoid.

Parameters

[in]	name	the name of the model.
[in]	path	(optional) directory for data file.

Exceptions

GeographicErr	if the data file cannot be found, is unreadable, or is corrupt.
GeographicErr	if the memory necessary for storing the model can't be allocated.

A filename is formed by appending ".wmm" (World Magnetic Model) to the name. If path is specified (and is non-empty), then the file is loaded from directory, path. Otherwise the path is given by the DefaultMagneticPath().

This file contains the metadata which specifies the properties of the model. The coefficients for the spherical harmonic sums are obtained from a file obtained by appending ".cof" to metadata file (so the filename ends in ".wwm.cof").

The model is not tied to a particular ellipsoidal model of the earth. The final earth argument to the constructor specifies an ellipsoid to allow geodetic coordinates to the transformed into the spherical coordinates used in the spherical harmonic sum.

Definition at line 64 of file dotnet/NETGeographicLib/MagneticModel.cpp.

NETGeographicLib::MagneticModel::~MagneticModel ( )

inline

The destructor calls the finalizer.

Definition at line 138 of file MagneticModel.h.

Member Function Documentation

MagneticCircle MagneticModel::Circle	(	double	t,
		double	lat,
		double	h
	)

Create a MagneticCircle object to allow the geomagnetic field at many points with constant lat, h, and t and varying lon to be computed efficiently.

Parameters

[in]	t	the time (years).
[in]	lat	latitude of the point (degrees).
[in]	h	the height of the point above the ellipsoid (meters).

Exceptions

std::bad_alloc

if the memory necessary for creating a MagneticCircle can't be allocated.

Returns

a MagneticCircle object whose MagneticCircle::Field(double lon) member function computes the field at particular values of lon.

If the field at several points on a circle of latitude need to be calculated then creating a MagneticCircle and using its member functions will be substantially faster, especially for high-degree models.

Definition at line 120 of file dotnet/NETGeographicLib/MagneticModel.cpp.

System::String MagneticModel::DefaultMagneticName ( )

static

Returns

the default name for the magnetic model.

This is the value of the environment variable GEOGRAPHICLIB_MAGNETIC_NAME, if set, otherwise, it is "wmm2015". The MagneticModel class does not use this function; it is just provided as a convenience for a calling program when constructing a MagneticModel object.

Definition at line 209 of file dotnet/NETGeographicLib/MagneticModel.cpp.

System::String MagneticModel::DefaultMagneticPath ( )

static

Returns

the default path for magnetic model data files.

This is the value of the environment variable GEOGRAPHICLIB_MAGNETIC_PATH, if set; otherwise, it is $GEOGRAPHICLIB_DATA/magnetic if the environment variable GEOGRAPHICLIB_DATA is set; otherwise, it is a compile-time default (/usr/local/share/GeographicLib/magnetic on non-Windows systems and C:/ProgramData/GeographicLib/magnetic on Windows systems).

Definition at line 203 of file dotnet/NETGeographicLib/MagneticModel.cpp.

void MagneticModel::Field	(	double	t,
		double	lat,
		double	lon,
		double	h,
		[System::Runtime::InteropServices::Out] double%	Bx,
		[System::Runtime::InteropServices::Out] double%	By,
		[System::Runtime::InteropServices::Out] double%	Bz
	)

Evaluate the components of the geomagnetic field.

Parameters

[in]	t	the time (years).
[in]	lat	latitude of the point (degrees).
[in]	lon	longitude of the point (degrees).
[in]	h	the height of the point above the ellipsoid (meters).
[out]	Bx	the easterly component of the magnetic field (nanotesla).
[out]	By	the northerly component of the magnetic field (nanotesla).
[out]	Bz	the vertical (up) component of the magnetic field (nanotesla).

Definition at line 88 of file dotnet/NETGeographicLib/MagneticModel.cpp.

void MagneticModel::Field	(	double	t,
		double	lat,
		double	lon,
		double	h,
		[System::Runtime::InteropServices::Out] double%	Bx,
		[System::Runtime::InteropServices::Out] double%	By,
		[System::Runtime::InteropServices::Out] double%	Bz,
		[System::Runtime::InteropServices::Out] double%	Bxt,
		[System::Runtime::InteropServices::Out] double%	Byt,
		[System::Runtime::InteropServices::Out] double%	Bzt
	)

Evaluate the components of the geomagnetic field and their time derivatives

Parameters

[in]	t	the time (years).
[in]	lat	latitude of the point (degrees).
[in]	lon	longitude of the point (degrees).
[in]	h	the height of the point above the ellipsoid (meters).
[out]	Bx	the easterly component of the magnetic field (nanotesla).
[out]	By	the northerly component of the magnetic field (nanotesla).
[out]	Bz	the vertical (up) component of the magnetic field (nanotesla).
[out]	Bxt	the rate of change of Bx (nT/yr).
[out]	Byt	the rate of change of By (nT/yr).
[out]	Bzt	the rate of change of Bz (nT/yr).

Definition at line 101 of file dotnet/NETGeographicLib/MagneticModel.cpp.

void MagneticModel::FieldComponents ( double  Bx, double  By, double  Bz, [System::Runtime::InteropServices::Out] double%  H, [System::Runtime::InteropServices::Out] double%  F, [System::Runtime::InteropServices::Out] double%  D, [System::Runtime::InteropServices::Out] double%  I  )

static

Compute various quantities dependent on the magnetic field.

Parameters

[in]	Bx	the x (easterly) component of the magnetic field (nT).
[in]	By	the y (northerly) component of the magnetic field (nT).
[in]	Bz	the z (vertical, up positive) component of the magnetic field (nT).
[out]	H	the horizontal magnetic field (nT).
[out]	F	the total magnetic field (nT).
[out]	D	the declination of the field (degrees east of north).
[out]	I	the inclination of the field (degrees down from horizontal).

Definition at line 133 of file dotnet/NETGeographicLib/MagneticModel.cpp.

void MagneticModel::FieldComponents ( double  Bx, double  By, double  Bz, double  Bxt, double  Byt, double  Bzt, [System::Runtime::InteropServices::Out] double%  H, [System::Runtime::InteropServices::Out] double%  F, [System::Runtime::InteropServices::Out] double%  D, [System::Runtime::InteropServices::Out] double%  I, [System::Runtime::InteropServices::Out] double%  Ht, [System::Runtime::InteropServices::Out] double%  Ft, [System::Runtime::InteropServices::Out] double%  Dt, [System::Runtime::InteropServices::Out] double%  It  )

static

Compute various quantities dependent on the magnetic field and its rate of change.

Parameters

[in]	Bx	the x (easterly) component of the magnetic field (nT).
[in]	By	the y (northerly) component of the magnetic field (nT).
[in]	Bz	the z (vertical, up positive) component of the magnetic field (nT).
[in]	Bxt	the rate of change of Bx (nT/yr).
[in]	Byt	the rate of change of By (nT/yr).
[in]	Bzt	the rate of change of Bz (nT/yr).
[out]	H	the horizontal magnetic field (nT).
[out]	F	the total magnetic field (nT).
[out]	D	the declination of the field (degrees east of north).
[out]	I	the inclination of the field (degrees down from horizontal).
[out]	Ht	the rate of change of H (nT/yr).
[out]	Ft	the rate of change of F (nT/yr).
[out]	Dt	the rate of change of D (degrees/yr).
[out]	It	the rate of change of I (degrees/yr).

Definition at line 148 of file dotnet/NETGeographicLib/MagneticModel.cpp.

Member Data Documentation

property System::String NETGeographicLib::MagneticModel::DateTime { System::String^ get()

Returns

date of the model, if available, from the ReleaseDate field in the data file; if absent, return "UNKNOWN".

Definition at line 270 of file MagneticModel.h.

property System::String NETGeographicLib::MagneticModel::Description { System::String^ get()

Returns

the description of the magnetic model, if available, from the Description file in the data file; if absent, return "NONE".

Definition at line 264 of file MagneticModel.h.

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

Returns

f the flattening of the ellipsoid. This is the value inherited from the Geocentric object used in the constructor.

Definition at line 343 of file MagneticModel.h.

const GeographicLib::MagneticModel* NETGeographicLib::MagneticModel::m_pMagneticModel

private

Definition at line 67 of file MagneticModel.h.

property System::String NETGeographicLib::MagneticModel::MagneticFile { System::String^ get()

Returns

full file name used to load the magnetic model.

Definition at line 275 of file MagneticModel.h.

property System::String NETGeographicLib::MagneticModel::MagneticModelDirectory { System::String^ get()

Returns

directory used to load the magnetic model.

Definition at line 286 of file MagneticModel.h.

property System::String NETGeographicLib::MagneticModel::MagneticModelName { System::String^ get()

Returns

"name" used to load the magnetic model (from the first argument of the constructor, but this may be overridden by the model file).

Definition at line 281 of file MagneticModel.h.

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

Returns

a the equatorial radius of the ellipsoid (meters). This is the value of a inherited from the Geocentric object used in the constructor.

Definition at line 337 of file MagneticModel.h.

property double NETGeographicLib::MagneticModel::MaxHeight { double get()

Returns

the maximum height above the ellipsoid (in meters) for which this MagneticModel should be used.

Because the model will typically provide useful results slightly outside the range of allowed heights, no check of t argument is made by MagneticModel::Field() or MagneticModel::Circle.

Definition at line 308 of file MagneticModel.h.

property double NETGeographicLib::MagneticModel::MaxTime { double get()

Returns

the maximum time (in years) for which this MagneticModel should be used.

Because the model will typically provide useful results slightly outside the range of allowed times, no check of t argument is made by MagneticModel::Field() or MagneticModel::Circle.

Definition at line 330 of file MagneticModel.h.

property double NETGeographicLib::MagneticModel::MinHeight { double get()

Returns

the minimum height above the ellipsoid (in meters) for which this MagneticModel should be used.

Because the model will typically provide useful results slightly outside the range of allowed heights, no check of t argument is made by MagneticModel::Field() or MagneticModel::Circle.

Definition at line 297 of file MagneticModel.h.

property double NETGeographicLib::MagneticModel::MinTime { double get()

Returns

the minimum time (in years) for which this MagneticModel should be used.

Because the model will typically provide useful results slightly outside the range of allowed times, no check of t argument is made by MagneticModel::Field() or MagneticModel::Circle.

Definition at line 319 of file MagneticModel.h.

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

• MagneticModel.h
• dotnet/NETGeographicLib/MagneticModel.cpp