diff options
author | William Joye <wjoye@cfa.harvard.edu> | 2018-01-09 19:28:07 (GMT) |
---|---|---|
committer | William Joye <wjoye@cfa.harvard.edu> | 2018-01-09 19:28:07 (GMT) |
commit | 3bfbbb90d4d6ebd44cc5eac38af24d1f78318a58 (patch) | |
tree | f278119398ae5d67a6a338705a76db420f6b8f7e /ast/erfa/eform.c | |
parent | 1332d38f2805d986ea130e43218c0d2e870b4dc1 (diff) | |
download | blt-3bfbbb90d4d6ebd44cc5eac38af24d1f78318a58.zip blt-3bfbbb90d4d6ebd44cc5eac38af24d1f78318a58.tar.gz blt-3bfbbb90d4d6ebd44cc5eac38af24d1f78318a58.tar.bz2 |
update ast 8.6.2
Diffstat (limited to 'ast/erfa/eform.c')
-rw-r--r-- | ast/erfa/eform.c | 155 |
1 files changed, 155 insertions, 0 deletions
diff --git a/ast/erfa/eform.c b/ast/erfa/eform.c new file mode 100644 index 0000000..0982ab4 --- /dev/null +++ b/ast/erfa/eform.c @@ -0,0 +1,155 @@ +#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. +** +*/ |