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/*============================================================================
*
* WCSLIB - an implementation of the FITS WCS proposal.
* Copyright (C) 1995-2002, Mark Calabretta
*
* This library is free software; you can redistribute it and/or modify it
* under the terms of the GNU Library General Public License as published
* by the Free Software Foundation; either version 2 of the License, or (at
* your option) any later version.
*
* This library 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 Library
* General Public License for more details.
*
* You should have received a copy of the GNU Library General Public License
* along with this library; if not, write to the Free Software Foundation,
* Inc., 51 Franklin Street,Fifth Floor, Boston, MA 02110-1301, USA
*
* Correspondence concerning WCSLIB may be directed to:
* Internet email: mcalabre@atnf.csiro.au
* Postal address: Dr. Mark Calabretta,
* Australia Telescope National Facility,
* P.O. Box 76,
* Epping, NSW, 2121,
* AUSTRALIA
*
*=============================================================================
*
* This version of wcstrig.c is based on the version in wcslib-2.9, but has
* been modified in the following ways by the Starlink project (e-mail:
* ussc@star.rl.ac.uk):
* - Support for non-ANSI C "const" class removed
* - Changed names of projection functions and degrees trig functions
* to avoid clashes with wcslib.
*=============================================================================
*
* The functions defined herein are trigonometric or inverse trigonometric
* functions which take or return angular arguments in decimal degrees.
*
* $Id$
*---------------------------------------------------------------------------*/
#include <math.h>
#include "wcsmath.h"
#include "wcstrig.h"
double astCosd(angle)
const double angle;
{
double resid;
resid = fabs(fmod(angle,360.0));
if (resid == 0.0) {
return 1.0;
} else if (resid == 90.0) {
return 0.0;
} else if (resid == 180.0) {
return -1.0;
} else if (resid == 270.0) {
return 0.0;
}
return cos(angle*D2R);
}
/*--------------------------------------------------------------------------*/
double astSind(angle)
const double angle;
{
double resid;
resid = fmod(angle-90.0,360.0);
if (resid == 0.0) {
return 1.0;
} else if (resid == 90.0) {
return 0.0;
} else if (resid == 180.0) {
return -1.0;
} else if (resid == 270.0) {
return 0.0;
}
return sin(angle*D2R);
}
/*--------------------------------------------------------------------------*/
double astTand(angle)
const double angle;
{
double resid;
resid = fmod(angle,360.0);
if (resid == 0.0 || fabs(resid) == 180.0) {
return 0.0;
} else if (resid == 45.0 || resid == 225.0) {
return 1.0;
} else if (resid == -135.0 || resid == -315.0) {
return -1.0;
}
return tan(angle*D2R);
}
/*--------------------------------------------------------------------------*/
double astACosd(v)
const double v;
{
if (v >= 1.0) {
if (v-1.0 < WCSTRIG_TOL) return 0.0;
} else if (v == 0.0) {
return 90.0;
} else if (v <= -1.0) {
if (v+1.0 > -WCSTRIG_TOL) return 180.0;
}
return acos(v)*R2D;
}
/*--------------------------------------------------------------------------*/
double astASind(v)
const double v;
{
if (v <= -1.0) {
if (v+1.0 > -WCSTRIG_TOL) return -90.0;
} else if (v == 0.0) {
return 0.0;
} else if (v >= 1.0) {
if (v-1.0 < WCSTRIG_TOL) return 90.0;
}
return asin(v)*R2D;
}
/*--------------------------------------------------------------------------*/
double astATand(v)
const double v;
{
if (v == -1.0) {
return -45.0;
} else if (v == 0.0) {
return 0.0;
} else if (v == 1.0) {
return 45.0;
}
return atan(v)*R2D;
}
/*--------------------------------------------------------------------------*/
double astATan2d(y, x)
const double x, y;
{
if (y == 0.0) {
if (x >= 0.0) {
return 0.0;
} else if (x < 0.0) {
return 180.0;
}
} else if (x == 0.0) {
if (y > 0.0) {
return 90.0;
} else if (y < 0.0) {
return -90.0;
}
}
return atan2(y,x)*R2D;
}
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