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Diffstat (limited to 'ast/wcstrig.c')
| -rw-r--r-- | ast/wcstrig.c | 189 |
1 files changed, 189 insertions, 0 deletions
diff --git a/ast/wcstrig.c b/ast/wcstrig.c new file mode 100644 index 0000000..d3ba400 --- /dev/null +++ b/ast/wcstrig.c @@ -0,0 +1,189 @@ +/*============================================================================ +* +* 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; +} |