| 1 | /*
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| 2 | *+
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| 3 | * Name:
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| 4 | * palDrange
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| 5 |
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| 6 | * Purpose:
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| 7 | * Normalize angle into range +/- pi
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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 | * palDrange( double angle )
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| 17 |
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| 18 | * Arguments:
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| 19 | * angle = double (Given)
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| 20 | * The angle in radians.
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| 21 |
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| 22 | * Description:
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| 23 | * The result is "angle" expressed in the range +/- pi. If the
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| 24 | * supplied value for "angle" is equal to +/- pi, it is returned
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| 25 | * unchanged.
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| 26 |
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| 27 | * Authors:
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| 28 | * DSB: David S Berry (JAC, Hawaii)
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| 29 | * PTW: Patrick T. Wallace
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| 30 | * {enter_new_authors_here}
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| 31 |
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| 32 | * History:
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| 33 | * 2012-05-09 (DSB):
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| 34 | * Initial version with documentation taken from Fortran SLA
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| 35 | * Adapted with permission from the Fortran SLALIB library.
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| 36 | * {enter_further_changes_here}
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| 37 |
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| 38 | * Copyright:
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| 39 | * Copyright (C) 1995 Rutherford Appleton Laboratory
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| 40 | * Copyright (C) 2012 Science and Technology Facilities Council.
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| 41 | * All Rights Reserved.
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| 42 |
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| 43 | * Licence:
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| 44 | * This program is free software: you can redistribute it and/or
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| 45 | * modify it under the terms of the GNU Lesser General Public
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| 46 | * License as published by the Free Software Foundation, either
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| 47 | * version 3 of the License, or (at your option) any later
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| 48 | * version.
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| 49 | *
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| 50 | * This program is distributed in the hope that it will be useful,
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| 51 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 52 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 53 | * GNU Lesser General Public License for more details.
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| 54 | *
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| 55 | * You should have received a copy of the GNU Lesser General
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| 56 | * License along with this program. If not, see
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| 57 | * <http://www.gnu.org/licenses/>.
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| 58 |
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| 59 | * Bugs:
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| 60 | * {note_any_bugs_here}
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| 61 | *-
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| 62 | */
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| 63 |
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| 64 | #include "pal.h"
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| 65 | #include "palmac.h"
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| 66 | #include <math.h>
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| 67 |
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| 68 | double palDrange( double angle ){
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| 69 | double result = fmod( angle, PAL__D2PI );
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| 70 | if( result > PAL__DPI ) {
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| 71 | result -= PAL__D2PI;
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| 72 | } else if( result < -PAL__DPI ) {
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| 73 | result += PAL__D2PI;
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| 74 | }
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| 75 | return result;
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| 76 | }
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| 77 |
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