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#include "erfa.h"
int eraEform ( int n, double *a, double *f )
/*
** - - - - - - - - -
** e r a E f o r m
** - - - - - - - - -
**
** Earth reference ellipsoids.
**
** Given:
** n int ellipsoid identifier (Note 1)
**
** Returned:
** a double equatorial radius (meters, Note 2)
** f double flattening (Note 2)
**
** Returned (function value):
** int status: 0 = OK
** -1 = illegal identifier (Note 3)
**
** Notes:
**
** 1) The identifier n is a number that specifies the choice of
** reference ellipsoid. The following are supported:
**
** n ellipsoid
**
** 1 ERFA_WGS84
** 2 ERFA_GRS80
** 3 ERFA_WGS72
**
** The n value has no significance outside the ERFA software. For
** convenience, symbols ERFA_WGS84 etc. are defined in erfam.h.
**
** 2) The ellipsoid parameters are returned in the form of equatorial
** radius in meters (a) and flattening (f). The latter is a number
** around 0.00335, i.e. around 1/298.
**
** 3) For the case where an unsupported n value is supplied, zero a and
** f are returned, as well as error status.
**
** References:
**
** Department of Defense World Geodetic System 1984, National
** Imagery and Mapping Agency Technical Report 8350.2, Third
** Edition, p3-2.
**
** Moritz, H., Bull. Geodesique 66-2, 187 (1992).
**
** The Department of Defense World Geodetic System 1972, World
** Geodetic System Committee, May 1974.
**
** Explanatory Supplement to the Astronomical Almanac,
** P. Kenneth Seidelmann (ed), University Science Books (1992),
** p220.
**
** Copyright (C) 2013-2016, NumFOCUS Foundation.
** Derived, with permission, from the SOFA library. See notes at end of file.
*/
{
/* Look up a and f for the specified reference ellipsoid. */
switch ( n ) {
case ERFA_WGS84:
*a = 6378137.0;
*f = 1.0 / 298.257223563;
break;
case ERFA_GRS80:
*a = 6378137.0;
*f = 1.0 / 298.257222101;
break;
case ERFA_WGS72:
*a = 6378135.0;
*f = 1.0 / 298.26;
break;
default:
/* Invalid identifier. */
*a = 0.0;
*f = 0.0;
return -1;
}
/* OK status. */
return 0;
}
/*----------------------------------------------------------------------
**
**
** Copyright (C) 2013-2016, NumFOCUS Foundation.
** All rights reserved.
**
** This library is derived, with permission, from the International
** Astronomical Union's "Standards of Fundamental Astronomy" library,
** available from http://www.iausofa.org.
**
** The ERFA version is intended to retain identical functionality to
** the SOFA library, but made distinct through different function and
** file names, as set out in the SOFA license conditions. The SOFA
** original has a role as a reference standard for the IAU and IERS,
** and consequently redistribution is permitted only in its unaltered
** state. The ERFA version is not subject to this restriction and
** therefore can be included in distributions which do not support the
** concept of "read only" software.
**
** Although the intent is to replicate the SOFA API (other than
** replacement of prefix names) and results (with the exception of
** bugs; any that are discovered will be fixed), SOFA is not
** responsible for any errors found in this version of the library.
**
** If you wish to acknowledge the SOFA heritage, please acknowledge
** that you are using a library derived from SOFA, rather than SOFA
** itself.
**
**
** TERMS AND CONDITIONS
**
** Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions
** are met:
**
** 1 Redistributions of source code must retain the above copyright
** notice, this list of conditions and the following disclaimer.
**
** 2 Redistributions in binary form must reproduce the above copyright
** notice, this list of conditions and the following disclaimer in
** the documentation and/or other materials provided with the
** distribution.
**
** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
** the International Astronomical Union nor the names of its
** contributors may be used to endorse or promote products derived
** from this software without specific prior written permission.
**
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
** ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
** POSSIBILITY OF SUCH DAMAGE.
**
*/
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