| [1672] | 1 | /* magfield.h -- compute local magnetic variation given position,
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 | 2 | **               altitude, and date
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 | 3 | **
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 | 4 | ** This is an implementation of the NIMA WMM 2000
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 | 5 | **
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 | 6 | **    http://www.nima.mil/GandG/ngdc-wmm2000.html
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 | 7 | **    For WMM2000 coefficients:
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 | 8 | **    ftp://ftp.ngdc.noaa.gov/Solid_Earth/Mainfld_Mag/DoD_Model/wmm.cof
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 | 9 | **    For IGRF/DGRF coefficients:
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 | 10 | **    http://swdcdb.kugi.kyoto-u.ac.jp/igrf/coef/igrfall.d
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 | 11 | **
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 | 12 | ** Copyright (C) 2000  Edward A Williams <Ed_Williams@compuserve.com>
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 | 13 | **
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 | 14 | ** Adapted from Excel 3.0 version 3/27/94 EAW
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 | 15 | ** Recoded in C++ by Starry Chan
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 | 16 | ** WMM95 added and rearranged in ANSI-C EAW 7/9/95
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 | 17 | ** Put shell around program and made Borland & GCC compatible EAW 11/22/95
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 | 18 | ** IGRF95 added 2/96 EAW
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 | 19 | ** WMM2000 IGR2000 added 2/00 EAW
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 | 20 | ** Released under GPL 3/26/00 EAW
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 | 21 | ** Adaptions and modifications for the SimGear project  3/27/2000 CLO
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 | 22 | **
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 | 23 | ** This program is free software; you can redistribute it and/or
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 | 24 | ** modify it under the terms of the GNU General Public License as
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 | 25 | ** published by the Free Software Foundation; either version 2 of the
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 | 26 | ** License, or (at your option) any later version.
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 | 27 | **
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 | 28 | ** This program is distributed in the hope that it will be useful, but
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 | 29 | ** WITHOUT ANY WARRANTY; without even the implied warranty of
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 | 30 | ** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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 | 31 | ** General Public License for more details.
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 | 32 | **
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 | 33 | ** You should have received a copy of the GNU General Public License
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 | 34 | ** along with this program; if not, write to the Free Software
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 | 35 | ** Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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 | 36 | **
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 | 37 | */
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 | 38 | #ifndef MAGFIELD_H
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 | 39 | #define MAGFIELD_H
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 | 40 | 
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 | 41 | #ifdef __cplusplus
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 | 42 | extern "C" {  /* extern "C" */
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 | 43 | #endif
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 | 44 | 
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 | 45 | /* Convert date to Julian day    1950-2049 */
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 | 46 | unsigned long int yymmdd_to_julian_days( int yy, int mm, int dd );
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 | 47 | 
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 | 48 | /* Convert degrees to radians */
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 | 49 | double deg_to_rad( double deg );
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 | 50 | 
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 | 51 | /* Convert radians to degrees */
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 | 52 | double rad_to_deg( double rad );
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 | 53 | 
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 | 54 | /* return variation (in radians) given geodetic latitude (radians), longitude
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 | 55 | (radians) ,height (km), (Julian) date and field model
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 | 56 | model=1 is IGRF90, 2 is WMM85, 3 is WMM90, 4 is WMM95, 5 is IGRF95, 
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 | 57 | 6 is WMM2000, 7 is IGRF2000
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 | 58 | N and E lat and long are positive, S and W negative
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 | 59 | */
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 | 60 | double SGMagVar( double lat, double lon, double h, long dat, int model, double* field );
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 | 61 | 
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 | 62 | #ifdef __cplusplus
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 | 63 | }             /* extern "C" */
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 | 64 | #endif
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 | 65 | 
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 | 66 | #endif
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