| 1 | /*
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| 2 | *+
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| 3 | * Name:
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| 4 | * palGeoc
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| 5 |
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| 6 | * Purpose:
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| 7 | * Convert geodetic position to geocentric
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| 8 |
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| 9 | * Language:
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| 10 | * Starlink ANSI C
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| 11 |
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| 12 | * Type of Module:
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| 13 | * Library routine
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| 14 |
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| 15 | * Invocation:
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| 16 | * void palGeoc( double p, double h, double * r, double *z );
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| 17 |
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| 18 | * Arguments:
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| 19 | * p = double (Given)
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| 20 | * latitude (radians)
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| 21 | * h = double (Given)
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| 22 | * height above reference spheroid (geodetic, metres)
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| 23 | * r = double * (Returned)
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| 24 | * distance from Earth axis (AU)
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| 25 | * z = double * (Returned)
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| 26 | * distance from plane of Earth equator (AU)
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| 27 |
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| 28 | * Description:
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| 29 | * Convert geodetic position to geocentric.
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| 30 |
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| 31 | * Authors:
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| 32 | * PTW: Patrick T. Wallace
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| 33 | * TIMJ: Tim Jenness (JAC, Hawaii)
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| 34 | * {enter_new_authors_here}
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| 35 |
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| 36 | * Notes:
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| 37 | * - Geocentric latitude can be obtained by evaluating atan2(z,r)
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| 38 | * - Uses WGS84 reference ellipsoid and calls eraGd2gc
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| 39 |
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| 40 | * History:
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| 41 | * 2012-03-01 (TIMJ):
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| 42 | * Initial version moved from palOne2One
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| 43 | * Adapted with permission from the Fortran SLALIB library.
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| 44 | * {enter_further_changes_here}
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| 45 |
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| 46 | * Copyright:
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| 47 | * Copyright (C) 2004 Patrick T. Wallace
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| 48 | * Copyright (C) 2012 Science and Technology Facilities Council.
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| 49 | * All Rights Reserved.
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| 50 |
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| 51 | * Licence:
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| 52 | * This program is free software: you can redistribute it and/or
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| 53 | * modify it under the terms of the GNU Lesser General Public
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| 54 | * License as published by the Free Software Foundation, either
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| 55 | * version 3 of the License, or (at your option) any later
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| 56 | * version.
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| 57 | *
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| 58 | * This program is distributed in the hope that it will be useful,
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| 59 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 60 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 61 | * GNU Lesser General Public License for more details.
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| 62 | *
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| 63 | * You should have received a copy of the GNU Lesser General
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| 64 | * License along with this program. If not, see
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| 65 | * <http://www.gnu.org/licenses/>.
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| 66 |
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| 67 | * Bugs:
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| 68 | * {note_any_bugs_here}
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| 69 | *-
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| 70 | */
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| 71 |
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| 72 | #include "pal.h"
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| 73 | #include "pal1sofa.h"
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| 74 |
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| 75 | void palGeoc ( double p, double h, double *r, double *z ) {
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| 76 | double xyz[3];
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| 77 | const double elong = 0.0; /* Use zero longitude */
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| 78 | const double AU = 1.49597870E11;
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| 79 | /* WGS84 looks to be the closest match */
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| 80 | eraGd2gc( ERFA_WGS84, elong, p, h, xyz );
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| 81 | *r = xyz[0] / (AU * cos(elong) );
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| 82 | *z = xyz[2] / AU;
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| 83 | }
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