gd2gce¶

erfa.gd2gce(a, f, elong, phi, height)[source]¶

Transform geodetic coordinates to geocentric for a reference ellipsoid of specified form.

Parameters:

adouble array
fdouble array
elongdouble array
phidouble array
heightdouble array

Returns:

xyzdouble array

Notes

Wraps ERFA function eraGd2gce. The ERFA documentation is:

- - - - - - - - - -
 e r a G d 2 g c e
- - - - - - - - - -

Transform geodetic coordinates to geocentric for a reference
ellipsoid of specified form.

Given:
   a       double     equatorial radius (Notes 1,3,4)
   f       double     flattening (Notes 2,4)
   elong   double     longitude (radians, east +ve, Note 4)
   phi     double     latitude (geodetic, radians, Note 4)
   height  double     height above ellipsoid (geodetic, Notes 3,4)

Returned:
   xyz     double[3]  geocentric vector (Note 3)

Returned (function value):
           int        status:  0 = OK
                              -1 = illegal case (Note 4)
Notes:

1) The equatorial radius, a, can be in any units, but meters is
   the conventional choice.

2) The flattening, f, is (for the Earth) a value around 0.00335,
   i.e. around 1/298.

3) The equatorial radius, a, and the height, height, must be
   given in the same units, and determine the units of the
   returned geocentric vector, xyz.

4) No validation is performed on individual arguments.  The error
   status -1 protects against (unrealistic) cases that would lead
   to arithmetic exceptions.  If an error occurs, xyz is unchanged.

5) The inverse transformation is performed in the function
   eraGc2gde.

6) The transformation for a standard ellipsoid (such as ERFA_WGS84) can
   more conveniently be performed by calling eraGd2gc,  which uses a
   numerical code to identify the required a and f values.

References:

   Green, R.M., Spherical Astronomy, Cambridge University Press,
   (1985) Section 4.5, p96.

   Explanatory Supplement to the Astronomical Almanac,
   P. Kenneth Seidelmann (ed), University Science Books (1992),
   Section 4.22, p202.

This revision:  2023 March 10

Copyright (C) 2013-2023, NumFOCUS Foundation.
Derived, with permission, from the SOFA library.  See notes at end of file.

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gd2gce¶