.NET wrapper for GeographicLib::NormalGravity. More...
#include <NETGeographicLib/NormalGravity.h>
Public Types | |
enum | StandardModels { WGS84, GRS80 } |
The enumerated standard gravity models. More... | |
Public Member Functions | |
~NormalGravity () | |
Setting up the normal gravity | |
NormalGravity (double a, double GM, double omega, double f, double J2) | |
NormalGravity (StandardModels model) | |
NormalGravity (const GeographicLib::NormalGravity &g) | |
Compute the gravity | |
double | SurfaceGravity (double lat) |
double | Gravity (double lat, double h,[System::Runtime::InteropServices::Out] double% gammay,[System::Runtime::InteropServices::Out] double% gammaz) |
double | U (double X, double Y, double Z,[System::Runtime::InteropServices::Out] double% gammaX,[System::Runtime::InteropServices::Out] double% gammaY,[System::Runtime::InteropServices::Out] double% gammaZ) |
double | V0 (double X, double Y, double Z,[System::Runtime::InteropServices::Out] double% GammaX,[System::Runtime::InteropServices::Out] double% GammaY,[System::Runtime::InteropServices::Out] double% GammaZ) |
double | Phi (double X, double Y,[System::Runtime::InteropServices::Out] double% fX,[System::Runtime::InteropServices::Out] double% fY) |
Static Public Member Functions | |
static NormalGravity^ | WGS84 () |
static NormalGravity^ | GRS80 () |
static double | J2ToFlattening (double a, double GM, double omega, double J2) |
static double | FlatteningToJ2 (double a, double GM, double omega, double f) |
Inspector functions | |
| |
double | MajorRadius [get] |
double | MassConstant [get] |
double | AngularVelocity [get] |
double | Flattening [get] |
double | EquatorialGravity [get] |
double | PolarGravity [get] |
double | GravityFlattening [get] |
double | SurfacePotential [get] |
double | DynamicalFormFactor (int n) |
Geocentric^ | Earth () |
.NET wrapper for GeographicLib::NormalGravity.
This class allows .NET applications to access GeographicLib::NormalGravity.
"Normal" gravity refers to an idealization of the earth which is modeled as an rotating ellipsoid. The eccentricity of the ellipsoid, the rotation speed, and the distribution of mass within the ellipsoid are such that the surface of the ellipsoid is a surface of constant potential (gravitational plus centrifugal). The acceleration due to gravity is therefore perpendicular to the surface of the ellipsoid.
There is a closed solution to this problem which is implemented here. Series "approximations" are only used to evaluate certain combinations of elementary functions where use of the closed expression results in a loss of accuracy for small arguments due to cancellation of the two leading terms. However these series include sufficient terms to give full machine precision.
Definitions:
References:
C# Example:
using System; using NETGeographicLib; namespace example_NormalGravity { class Program { static void Main(string[] args) { try { NormalGravity grav = new NormalGravity(NormalGravity.StandardModels.WGS84); double lat = 27.99, h = 8820; // Mt Everest double gammay, gammaz; grav.Gravity(lat, h, out gammay, out gammaz); Console.WriteLine(String.Format("{0} {1}", gammay, gammaz)); } catch (GeographicErr e) { Console.WriteLine(String.Format("Caught exception: {0}", e.Message)); } } } }
Managed C++ Example:
using namespace System; using namespace NETGeographicLib; int main(array<System::String ^> ^/*args*/) { try { NormalGravity^ grav = gcnew NormalGravity(NormalGravity::StandardModels::WGS84); double lat = 27.99, h = 8820; // Mt Everest double gammay, gammaz; grav->Gravity(lat, h, gammay, gammaz); Console::WriteLine(String::Format("{0} {1}", gammay, gammaz)); } catch (GeographicErr^ e) { Console::WriteLine(String::Format("Caught exception: {0}", e->Message)); return -1; } return 0; }
Visual Basic Example:
Imports NETGeographicLib Module example_NormalGravity Sub Main() Try Dim grav As NormalGravity = New NormalGravity(NormalGravity.StandardModels.WGS84) Dim lat As Double = 27.99, h = 8820 ' Mt Everest Dim gammay, gammaz As Double grav.Gravity(lat, h, gammay, gammaz) Console.WriteLine(String.Format("{0} {1}", gammay, gammaz)) Catch ex As GeographicErr Console.WriteLine(String.Format("Caught exception: {0}", ex.Message)) End Try End Sub End Module
INTERFACE DIFFERENCES:
A constructor has been provided for creating standard WGS84 and GRS80 gravity models.
The following functions are implemented as properties: MajorRadius, MassConstant, AngularVelocity, Flattening, EquatorialGravity, PolarGravity, GravityFlattening, SurfacePotential.
Definition at line 71 of file NormalGravity.h.
The enumerated standard gravity models.
Definition at line 81 of file NormalGravity.h.
NETGeographicLib::NormalGravity::NormalGravity | ( | double | a, | |
double | GM, | |||
double | omega, | |||
double | f, | |||
double | J2 | |||
) |
Constructor for the normal gravity.
[in] | a | equatorial radius (meters). |
[in] | GM | mass constant of the ellipsoid (meters3/seconds2); this is the product of G the gravitational constant and M the mass of the earth (usually including the mass of the earth's atmosphere). |
[in] | omega | the angular velocity (rad s1). |
[in] | f | the flattening of the ellipsoid. |
[in] | J2 | dynamical form factor. |
if | a is not positive or the other constants are inconsistent (see below). |
Exactly one of f and J2 should be positive and this will be used to define the ellipsoid. The shape of the ellipsoid can be given in one of two ways:
Referenced by ~NormalGravity().
NETGeographicLib::NormalGravity::NormalGravity | ( | StandardModels | model | ) |
A constructor for creating standard gravity models..
[in] | model | Specifies the desired model. |
NETGeographicLib::NormalGravity::NormalGravity | ( | const GeographicLib::NormalGravity & | g | ) |
A constructor that accepts a GeographicLib::NormalGravity. For internal use only.
g | An existing GeographicLib::NormalGravity. |
NETGeographicLib::NormalGravity::~NormalGravity | ( | ) | [inline] |
The destructor calls the finalizer.
Definition at line 134 of file NormalGravity.h.
References NormalGravity().
double NETGeographicLib::NormalGravity::SurfaceGravity | ( | double | lat | ) |
Evaluate the gravity on the surface of the ellipsoid.
[in] | lat | the geographic latitude (degrees). |
Due to the axial symmetry of the ellipsoid, the result is independent of the value of the longitude. This acceleration is perpendicular to the surface of the ellipsoid. It includes the effects of the earth's rotation.
double NETGeographicLib::NormalGravity::Gravity | ( | double | lat, | |
double | h, | |||
[System::Runtime::InteropServices::Out] double% | gammay, | |||
[System::Runtime::InteropServices::Out] double% | gammaz | |||
) |
Evaluate the gravity at an arbitrary point above (or below) the ellipsoid.
[in] | lat | the geographic latitude (degrees). |
[in] | h | the height above the ellipsoid (meters). |
[out] | gammay | the northerly component of the acceleration (m s2). |
[out] | gammaz | the upward component of the acceleration (m s2); this is usually negative. |
Due to the axial symmetry of the ellipsoid, the result is independent of the value of the longitude and the easterly component of the acceleration vanishes, gammax = 0. The function includes the effects of the earth's rotation. When h = 0, this function gives gammay = 0 and the returned value matches that of NormalGravity::SurfaceGravity.
double NETGeographicLib::NormalGravity::U | ( | double | X, | |
double | Y, | |||
double | Z, | |||
[System::Runtime::InteropServices::Out] double% | gammaX, | |||
[System::Runtime::InteropServices::Out] double% | gammaY, | |||
[System::Runtime::InteropServices::Out] double% | gammaZ | |||
) |
Evaluate the components of the acceleration due to gravity and the centrifugal acceleration in geocentric coordinates.
[in] | X | geocentric coordinate of point (meters). |
[in] | Y | geocentric coordinate of point (meters). |
[in] | Z | geocentric coordinate of point (meters). |
[out] | gammaX | the X component of the acceleration (m s2). |
[out] | gammaY | the Y component of the acceleration (m s2). |
[out] | gammaZ | the Z component of the acceleration (m s2). |
The acceleration given by = U = V0 + = + f.
double NETGeographicLib::NormalGravity::V0 | ( | double | X, | |
double | Y, | |||
double | Z, | |||
[System::Runtime::InteropServices::Out] double% | GammaX, | |||
[System::Runtime::InteropServices::Out] double% | GammaY, | |||
[System::Runtime::InteropServices::Out] double% | GammaZ | |||
) |
Evaluate the components of the acceleration due to gravity alone in geocentric coordinates.
[in] | X | geocentric coordinate of point (meters). |
[in] | Y | geocentric coordinate of point (meters). |
[in] | Z | geocentric coordinate of point (meters). |
[out] | GammaX | the X component of the acceleration due to gravity (m s2). |
[out] | GammaY | the Y component of the acceleration due to gravity (m s2). |
[out] | GammaZ | the Z component of the acceleration due to gravity (m s2). |
This function excludes the centrifugal acceleration and is appropriate to use for space applications. In terrestrial applications, the function NormalGravity::U (which includes this effect) should usually be used.
double NETGeographicLib::NormalGravity::Phi | ( | double | X, | |
double | Y, | |||
[System::Runtime::InteropServices::Out] double% | fX, | |||
[System::Runtime::InteropServices::Out] double% | fY | |||
) |
Evaluate the centrifugal acceleration in geocentric coordinates.
[in] | X | geocentric coordinate of point (meters). |
[in] | Y | geocentric coordinate of point (meters). |
[out] | fX | the X component of the centrifugal acceleration (m s2). |
[out] | fY | the Y component of the centrifugal acceleration (m s2). |
is independent of Z, thus fZ = 0. This function NormalGravity::U sums the results of NormalGravity::V0 and NormalGravity::Phi.
double NETGeographicLib::NormalGravity::DynamicalFormFactor | ( | int | n | ) |
If n = 2 (the default), this is the value of J2 used in the constructor. Otherwise it is the zonal coefficient of the Legendre harmonic sum of the normal gravitational potential. Note that Jn = 0 if n is odd. In most gravity applications, fully normalized Legendre functions are used and the corresponding coefficient is Cn0 = Jn / sqrt(2 n + 1).
Geocentric ^ NETGeographicLib::NormalGravity::Earth | ( | ) |
static NormalGravity ^ NETGeographicLib::NormalGravity::WGS84 | ( | ) | [static] |
A global instantiation of NormalGravity for the WGS84 ellipsoid.
static NormalGravity ^ NETGeographicLib::NormalGravity::GRS80 | ( | ) | [static] |
A global instantiation of NormalGravity for the GRS80 ellipsoid.
static double NETGeographicLib::NormalGravity::J2ToFlattening | ( | double | a, | |
double | GM, | |||
double | omega, | |||
double | J2 | |||
) | [static] |
Compute the flattening from the dynamical form factor.
[in] | a | equatorial radius (meters). |
[in] | GM | mass constant of the ellipsoid (meters3/seconds2); this is the product of G the gravitational constant and M the mass of the earth (usually including the mass of the earth's atmosphere). |
[in] | omega | the angular velocity (rad s1). |
[in] | J2 | the dynamical form factor. |
static double NETGeographicLib::NormalGravity::FlatteningToJ2 | ( | double | a, | |
double | GM, | |||
double | omega, | |||
double | f | |||
) | [static] |
Compute the dynamical form factor from the flattening.
[in] | a | equatorial radius (meters). |
[in] | GM | mass constant of the ellipsoid (meters3/seconds2); this is the product of G the gravitational constant and M the mass of the earth (usually including the mass of the earth's atmosphere). |
[in] | omega | the angular velocity (rad s1). |
[in] | f | the flattening of the ellipsoid. |
double NETGeographicLib::NormalGravity::MajorRadius [get] |
Definition at line 255 of file NormalGravity.h.
double NETGeographicLib::NormalGravity::MassConstant [get] |
Definition at line 262 of file NormalGravity.h.
double NETGeographicLib::NormalGravity::AngularVelocity [get] |
Definition at line 281 of file NormalGravity.h.
double NETGeographicLib::NormalGravity::Flattening [get] |
Definition at line 287 of file NormalGravity.h.
double NETGeographicLib::NormalGravity::EquatorialGravity [get] |
Definition at line 293 of file NormalGravity.h.
double NETGeographicLib::NormalGravity::PolarGravity [get] |
Definition at line 299 of file NormalGravity.h.
double NETGeographicLib::NormalGravity::GravityFlattening [get] |
Definition at line 305 of file NormalGravity.h.
double NETGeographicLib::NormalGravity::SurfacePotential [get] |
Definition at line 311 of file NormalGravity.h.