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wcstrig.h
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/*============================================================================
WCSLIB 8.4 - an implementation of the FITS WCS standard.
Copyright (C) 1995-2024, Mark Calabretta
This file is part of WCSLIB.
WCSLIB is free software: you can redistribute it and/or modify it under the
terms of the GNU Lesser General Public License as published by the Free
Software Foundation, either version 3 of the License, or (at your option)
any later version.
WCSLIB is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for
more details.
You should have received a copy of the GNU Lesser General Public License
along with WCSLIB. If not, see http://www.gnu.org/licenses.
Author: Mark Calabretta, Australia Telescope National Facility, CSIRO.
http://www.atnf.csiro.au/people/Mark.Calabretta
$Id: wcstrig.h,v 8.4 2024/10/28 13:56:16 mcalabre Exp $
*=============================================================================
*
* WCSLIB 8.4 - C routines that implement the FITS World Coordinate System
* (WCS) standard. Refer to the README file provided with WCSLIB for an
* overview of the library.
*
*
* Summary of the wcstrig routines
* -------------------------------
* When dealing with celestial coordinate systems and spherical projections
* (some moreso than others) it is often desirable to use an angular measure
* that provides an exact representation of the latitude of the north or south
* pole. The WCSLIB routines use the following trigonometric functions that
* take or return angles in degrees:
*
* - cosd()
* - sind()
* - tand()
* - acosd()
* - asind()
* - atand()
* - atan2d()
* - sincosd()
*
* These "trigd" routines are expected to handle angles that are a multiple of
* 90 degrees returning an exact result. Some C implementations provide these
* as part of a system library and in such cases it may (or may not!) be
* preferable to use them. WCSLIB provides wrappers on the standard trig
* functions based on radian measure, adding tests for multiples of 90 degrees.
*
* However, wcstrig.h also provides the choice of using preprocessor macro
* implementations of the trigd functions that don't test for multiples of
* 90 degrees (compile with -DWCSTRIG_MACRO). These are typically 20% faster
* but may lead to problems near the poles.
*
*
* cosd() - Cosine of an angle in degrees
* --------------------------------------
* cosd() returns the cosine of an angle given in degrees.
*
* Given:
* angle double [deg].
*
* Function return value:
* double Cosine of the angle.
*
*
* sind() - Sine of an angle in degrees
* ------------------------------------
* sind() returns the sine of an angle given in degrees.
*
* Given:
* angle double [deg].
*
* Function return value:
* double Sine of the angle.
*
*
* sincosd() - Sine and cosine of an angle in degrees
* --------------------------------------------------
* sincosd() returns the sine and cosine of an angle given in degrees.
*
* Given:
* angle double [deg].
*
* Returned:
* sin *double Sine of the angle.
*
* cos *double Cosine of the angle.
*
* Function return value:
* void
*
*
* tand() - Tangent of an angle in degrees
* ---------------------------------------
* tand() returns the tangent of an angle given in degrees.
*
* Given:
* angle double [deg].
*
* Function return value:
* double Tangent of the angle.
*
*
* acosd() - Inverse cosine, returning angle in degrees
* ----------------------------------------------------
* acosd() returns the inverse cosine in degrees.
*
* Given:
* x double in the range [-1,1].
*
* Function return value:
* double Inverse cosine of x [deg].
*
*
* asind() - Inverse sine, returning angle in degrees
* --------------------------------------------------
* asind() returns the inverse sine in degrees.
*
* Given:
* y double in the range [-1,1].
*
* Function return value:
* double Inverse sine of y [deg].
*
*
* atand() - Inverse tangent, returning angle in degrees
* -----------------------------------------------------
* atand() returns the inverse tangent in degrees.
*
* Given:
* s double
*
* Function return value:
* double Inverse tangent of s [deg].
*
*
* atan2d() - Polar angle of (x,y), in degrees
* -------------------------------------------
* atan2d() returns the polar angle, beta, in degrees, of polar coordinates
* (rho,beta) corresponding to Cartesian coordinates (x,y). It is equivalent
* to the arg(x,y) function of WCS Paper II, though with transposed arguments.
*
* Given:
* y double Cartesian y-coordinate.
*
* x double Cartesian x-coordinate.
*
* Function return value:
* double Polar angle of (x,y) [deg].
*
*===========================================================================*/
#ifndef WCSLIB_WCSTRIG
#define WCSLIB_WCSTRIG
#include <math.h>
#include "wcsconfig.h"
#ifdef HAVE_SINCOS
void sincos(double angle, double *sin, double *cos);
#endif
#ifdef __cplusplus
extern "C" {
#endif
#ifdef WCSTRIG_MACRO
// Macro implementation of the trigd functions.
#include "wcsmath.h"
#define cosd(X) cos((X)*D2R)
#define sind(X) sin((X)*D2R)
#define tand(X) tan((X)*D2R)
#define acosd(X) acos(X)*R2D
#define asind(X) asin(X)*R2D
#define atand(X) atan(X)*R2D
#define atan2d(Y,X) atan2(Y,X)*R2D
#ifdef HAVE_SINCOS
#define sincosd(X,S,C) sincos((X)*D2R,(S),(C))
#else
#define sincosd(X,S,C) *(S) = sin((X)*D2R); *(C) = cos((X)*D2R);
#endif
#else
// Use WCSLIB wrappers or native trigd functions.
double cosd(double angle);
double sind(double angle);
void sincosd(double angle, double *sin, double *cos);
double tand(double angle);
double acosd(double x);
double asind(double y);
double atand(double s);
double atan2d(double y, double x);
// Domain tolerance for asin() and acos() functions.
#define WCSTRIG_TOL 1e-10
#endif // WCSTRIG_MACRO
#ifdef __cplusplus
}
#endif
#endif // WCSLIB_WCSTRIG
wcsmath.h
sind
double sind(double angle)
Sine of an angle in degrees.
cosd
double cosd(double angle)
Cosine of an angle in degrees.
tand
double tand(double angle)
Tangent of an angle in degrees.
asind
double asind(double y)
Inverse sine, returning angle in degrees.
atand
double atand(double s)
Inverse tangent, returning angle in degrees.
acosd
double acosd(double x)
Inverse cosine, returning angle in degrees.
atan2d
double atan2d(double y, double x)
Polar angle of , in degrees.
sincosd
void sincosd(double angle, double *sin, double *cos)
Sine and cosine of an angle in degrees.