.TH LIBTELLURIAN.H 0 libtellurian
.SH NAME
libtellurian.h \- Geodesy library header
.SH SYNPOSIS
.nf
#include <libtellurian.h>
#define LIBTELLURIAN_EQUATORIAL_RADIUS 6378137.0
#define LIBTELLURIAN_POLAR_RADIUS 6356752.314245
#define LIBTELLURIAN_MEAN_RADIUS /* derived value omitted */
#define LIBTELLURIAN_VOLUMETRIC_RADIUS /* derived value omitted */
#define LIBTELLURIAN_AUTHALIC_RADIUS /* derived value omitted */
#define LIBTELLURIAN_RECTIFYING_RADIUS /* derived value omitted */
#define LIBTELLURIAN_NOMINAL_EQUATORIAL_RADIUS 6378100.
#define LIBTELLURIAN_NOMINAL_POLAR_RADIUS 6356800.
#define LIBTELLURIAN_NOMINAL_RADIUS LIBTELLURIAN_NOMINAL_EQUATORIAL_RADIUS
#define LIBTELLURIAN_EQUATORIAL_CIRCUMFERENCE /* derived value omitted */
#define LIBTELLURIAN_POLAR_CIRCUMFERENCE /* derived value omitted */
#define LIBTELLURIAN_MEAN_CIRCUMFERENCE /* derived value omitted */
#define LIBTELLURIAN_VOLUMETRIC_CIRCUMFERENCE /* derived value omitted */
#define LIBTELLURIAN_AUTHALIC_CIRCUMFERENCE /* derived value omitted */
#define LIBTELLURIAN_MERIDIONAL_CIRCUMFERENCE /* derived value omitted */
#define LIBTELLURIAN_EQUATORIAL_GRAVITY 9.7803253359
#define LIBTELLURIAN_POLAR_GRAVITY 9.8321849378
#define LIBTELLURIAN_NORMAL_EQUATORIAL_GRAVITY /* derived value omitted */
#define LIBTELLURIAN_NORMAL_POLAR_GRAVITY LIBTELLURIAN_POLAR_GRAVITY
#define LIBTELLURIAN_MASS_OF_EARTH 5.972168e24
#define LIBTELLURIAN_ANGULAR_VELOCITY 7.292115e-5
#define LIBTELLURIAN_GEOCENTRIC_GRAVITATIONAL_CONSTANT 3.986004418e14
.fi
.PP
Link with
.I -ltellurian
.IR -lm .
.SH DESCRIPTION
.B libtellurian.h
provides a collection of constants useful for geodesy:
.TP
.B LIBTELLURIAN_EQUATORIAL_RADIUS
The Earth's semimajor axes, in meters, which is the radius
of the of the circle formed by the Earth's equator, when
modelled as a spheroid.
This value is a measurement and is subject to refinement.
.TP
.B LIBTELLURIAN_POLAR_RADIUS
The Earth's semiminor axis, in meters, which is the distance
the center of the Earth, when modelled as a spheroid, and
either pole.
This value is a measurement and is subject to refinement.
.TP
.B LIBTELLURIAN_MEAN_RADIUS
The arithmetic mean of
.I LIBTELLURIAN_EQUATORIAL_RADIUS
and
.IR LIBTELLURIAN_POLAR_RADIUS .
.TP
.B LIBTELLURIAN_VOLUMETRIC_RADIUS
The geometric mean of
.I LIBTELLURIAN_EQUATORIAL_RADIUS
and
.IR LIBTELLURIAN_POLAR_RADIUS ,
which is the radius of a sphere with the same volume as
the Earth.
.TP
.B LIBTELLURIAN_AUTHALIC_RADIUS
The radius, in meters, of a sphere with the same area
as the Earth.
This is a value derived from
.I LIBTELLURIAN_EQUATORIAL_RADIUS
and
.IR LIBTELLURIAN_POLAR_RADIUS .
.TP
.B LIBTELLURIAN_RECTIFYING_RADIUS
The radius, in meters, of a sphere with the same
circumference as the a great ellipse, on the Earth's
ellipsoid, intersecting with both poles (the
meridional circumference).
This is a value derived from
.I LIBTELLURIAN_EQUATORIAL_RADIUS
and
.IR LIBTELLURIAN_POLAR_RADIUS .
.TP
.B LIBTELLURIAN_NOMINAL_EQUATORIAL_RADIUS
The Earth's nominal equatorial radius, in meters,
which is a standardised approximate value of
.IR LIBTELLURIAN_EQUATORIAL_RADIUS .
.TP
.B LIBTELLURIAN_NOMINAL_POLAR_RADIUS
The Earth's nominal polar radius, in meters,
which is a standardised approximate value of
.IR LIBTELLURIAN_POLAR_RADIUS .
.TP
.B LIBTELLURIAN_NOMINAL_RADIUS
The Earth's nominal radius, in meters, which is
a standardised approximate value of
.IR LIBTELLURIAN_EQUATORIAL_RADIUS ,
and is a synonym for
.IR LIBTELLURIAN_NOMINAL_EQUATORIAL_RADIUS .
.TP
.B LIBTELLURIAN_EQUATORIAL_CIRCUMFERENCE
The circumference, in meters, of a circle with the radius
.IR LIBTELLURIAN_EQUATORIAL_RADIUS .
.TP
.B LIBTELLURIAN_POLAR_CIRCUMFERENCE
The circumference, in meters, of a circle with the radius
.IR LIBTELLURIAN_POLAR_RADIUS .
.TP
.B LIBTELLURIAN_MEAN_CIRCUMFERENCE
The circumference, in meters, of a circle with the radius
.IR LIBTELLURIAN_MEAN_RADIUS .
.TP
.B LIBTELLURIAN_VOLUMETRIC_CIRCUMFERENCE
The circumference, in meters, of a circle with the radius
.IR LIBTELLURIAN_VOLUMETRIC_RADIUS .
.TP
.B LIBTELLURIAN_AUTHALIC_CIRCUMFERENCE
The circumference, in meters, of a circle with the radius
.IR LIBTELLURIAN_AUTHALIC_RADIUS .
.TP
.B LIBTELLURIAN_MERIDIONAL_CIRCUMFERENCE
The circumference, in meters, of a circle with the radius
.IR LIBTELLURIAN_RECTIFYING_RADIUS .
.TP
.B LIBTELLURIAN_EQUATORIAL_GRAVITY
The Earth's gravity, in meters per square second, at the equator.
This value is a measurement and is subject to refinement.
.TP
.B LIBTELLURIAN_POLAR_GRAVITY
The Earth's gravity, in meters per square second, at the poles.
This value is a measurement and is subject to refinement.
.TP
.B LIBTELLURIAN_NORMAL_EQUATORIAL_GRAVITY
The Earth's normal gravity, in meters per square second, at
the equator. This is a gravity theoretical gravitational
acceleration at the Earth's ellipsoid unaffected by rotation
and assuming the Earth's is spheroidal.
This value is derived from
.IR LIBTELLURIAN_EQUATORIAL_GRAVITY ,
.IR LIBTELLURIAN_EQUATORIAL_RADIUS ,
and
.IR LIBTELLURIAN_ANGULAR_VELOCITY .
.TP
.B LIBTELLURIAN_NORMAL_POLAR_GRAVITY
The Earth's normal gravity, in meters per square second, at
the poles. This is a gravity theoretical gravitational
acceleration at the Earth's ellipsoid unaffected by rotation
and assuming the Earth's is spheroidal.
This is an alias for a measurement and is subject to refinement.
.TP
.B LIBTELLURIAN_MASS_OF_EARTH
The mass of the Earth, in kilograms.
This value is a measurement and is subject to refinement.
.TP
.B LIBTELLURIAN_ANGULAR_VELOCITY
The Earth's nominal mean angular velocity, in radians per second.
This value is a measurement and is subject to refinement.
.TP
.B LIBTELLURIAN_GEOCENTRIC_GRAVITATIONAL_CONSTANT
The geocentric gravitational constant, in cubic meters per square
second. This is the product of the (universal) gravitational
constant and the Earth's mass, however this value is more reliable
than both the mass of the Earth and the (even less reliable)
universal gravitational constant.
This value is a measurement and is subject to refinement.
.PP
.B libtellurian.h
also defines a number of geodesy functions. See
.BR libtellurian (7)
for more information.
.SH SEE ALSO
.BR libtellurian (7),
.BR libtellurian_sea_level (3),
.BR libtellurian_coarse_distance (3),
.BR libtellurian_distance (3),
.BR libtellurian_end_point (3),
.BR libtellurian_normal_gravity (3),
.BR libtellurian_elevated_gravity (3),
.BR libtellurian_meridian_radius (3),
.BR libtellurian_transverse_radius (3),
.BR libtellurian_azimuthal_radius (3),
.BR libtellurian_gaussian_radius (3)
