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<h1>wcstrig.h</h1><a href="wcstrig_8h.html">Go to the documentation of this file.</a><div class="fragment"><pre class="fragment"><a name="l00001"></a>00001 <span class="comment">/*============================================================================</span>
<a name="l00002"></a>00002 <span class="comment"></span>
<a name="l00003"></a>00003 <span class="comment">  WCSLIB 4.8 - an implementation of the FITS WCS standard.</span>
<a name="l00004"></a>00004 <span class="comment">  Copyright (C) 1995-2011, Mark Calabretta</span>
<a name="l00005"></a>00005 <span class="comment"></span>
<a name="l00006"></a>00006 <span class="comment">  This file is part of WCSLIB.</span>
<a name="l00007"></a>00007 <span class="comment"></span>
<a name="l00008"></a>00008 <span class="comment">  WCSLIB is free software: you can redistribute it and/or modify it under the</span>
<a name="l00009"></a>00009 <span class="comment">  terms of the GNU Lesser General Public License as published by the Free</span>
<a name="l00010"></a>00010 <span class="comment">  Software Foundation, either version 3 of the License, or (at your option)</span>
<a name="l00011"></a>00011 <span class="comment">  any later version.</span>
<a name="l00012"></a>00012 <span class="comment"></span>
<a name="l00013"></a>00013 <span class="comment">  WCSLIB is distributed in the hope that it will be useful, but WITHOUT ANY</span>
<a name="l00014"></a>00014 <span class="comment">  WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS</span>
<a name="l00015"></a>00015 <span class="comment">  FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for</span>
<a name="l00016"></a>00016 <span class="comment">  more details.</span>
<a name="l00017"></a>00017 <span class="comment"></span>
<a name="l00018"></a>00018 <span class="comment">  You should have received a copy of the GNU Lesser General Public License</span>
<a name="l00019"></a>00019 <span class="comment">  along with WCSLIB.  If not, see &lt;http://www.gnu.org/licenses/&gt;.</span>
<a name="l00020"></a>00020 <span class="comment"></span>
<a name="l00021"></a>00021 <span class="comment">  Correspondence concerning WCSLIB may be directed to:</span>
<a name="l00022"></a>00022 <span class="comment">    Internet email: mcalabre@atnf.csiro.au</span>
<a name="l00023"></a>00023 <span class="comment">    Postal address: Dr. Mark Calabretta</span>
<a name="l00024"></a>00024 <span class="comment">                    Australia Telescope National Facility, CSIRO</span>
<a name="l00025"></a>00025 <span class="comment">                    PO Box 76</span>
<a name="l00026"></a>00026 <span class="comment">                    Epping NSW 1710</span>
<a name="l00027"></a>00027 <span class="comment">                    AUSTRALIA</span>
<a name="l00028"></a>00028 <span class="comment"></span>
<a name="l00029"></a>00029 <span class="comment">  Author: Mark Calabretta, Australia Telescope National Facility</span>
<a name="l00030"></a>00030 <span class="comment">  http://www.atnf.csiro.au/~mcalabre/index.html</span>
<a name="l00031"></a>00031 <span class="comment">  $Id: wcstrig.h,v 4.8.1.1 2011/08/15 08:07:06 cal103 Exp cal103 $</span>
<a name="l00032"></a>00032 <span class="comment">*=============================================================================</span>
<a name="l00033"></a>00033 <span class="comment">*</span>
<a name="l00034"></a>00034 <span class="comment">* Summary of the wcstrig routines</span>
<a name="l00035"></a>00035 <span class="comment">* -------------------------------</span>
<a name="l00036"></a>00036 <span class="comment">* When dealing with celestial coordinate systems and spherical projections</span>
<a name="l00037"></a>00037 <span class="comment">* (some moreso than others) it is often desirable to use an angular measure</span>
<a name="l00038"></a>00038 <span class="comment">* that provides an exact representation of the latitude of the north or south</span>
<a name="l00039"></a>00039 <span class="comment">* pole.  The WCSLIB routines use the following trigonometric functions that</span>
<a name="l00040"></a>00040 <span class="comment">* take or return angles in degrees:</span>
<a name="l00041"></a>00041 <span class="comment">*</span>
<a name="l00042"></a>00042 <span class="comment">*   - cosd()</span>
<a name="l00043"></a>00043 <span class="comment">*   - sind()</span>
<a name="l00044"></a>00044 <span class="comment">*   - tand()</span>
<a name="l00045"></a>00045 <span class="comment">*   - acosd()</span>
<a name="l00046"></a>00046 <span class="comment">*   - asind()</span>
<a name="l00047"></a>00047 <span class="comment">*   - atand()</span>
<a name="l00048"></a>00048 <span class="comment">*   - atan2d()</span>
<a name="l00049"></a>00049 <span class="comment">*   - sincosd()</span>
<a name="l00050"></a>00050 <span class="comment">*</span>
<a name="l00051"></a>00051 <span class="comment">* These "trigd" routines are expected to handle angles that are a multiple of</span>
<a name="l00052"></a>00052 <span class="comment">* 90 degrees returning an exact result.  Some C implementations provide these</span>
<a name="l00053"></a>00053 <span class="comment">* as part of a system library and in such cases it may (or may not!) be</span>
<a name="l00054"></a>00054 <span class="comment">* preferable to use them.  WCSLIB provides wrappers on the standard trig</span>
<a name="l00055"></a>00055 <span class="comment">* functions based on radian measure, adding tests for multiples of 90 degrees.</span>
<a name="l00056"></a>00056 <span class="comment">*</span>
<a name="l00057"></a>00057 <span class="comment">* However, wcstrig.h also provides the choice of using preprocessor macro</span>
<a name="l00058"></a>00058 <span class="comment">* implementations of the trigd functions that don't test for multiples of</span>
<a name="l00059"></a>00059 <span class="comment">* 90 degrees (compile with -DWCSTRIG_MACRO).  These are typically 20% faster</span>
<a name="l00060"></a>00060 <span class="comment">* but may lead to problems near the poles.</span>
<a name="l00061"></a>00061 <span class="comment">*</span>
<a name="l00062"></a>00062 <span class="comment">*</span>
<a name="l00063"></a>00063 <span class="comment">* cosd() - Cosine of an angle in degrees</span>
<a name="l00064"></a>00064 <span class="comment">* --------------------------------------</span>
<a name="l00065"></a>00065 <span class="comment">* cosd() returns the cosine of an angle given in degrees.</span>
<a name="l00066"></a>00066 <span class="comment">*</span>
<a name="l00067"></a>00067 <span class="comment">* Given:</span>
<a name="l00068"></a>00068 <span class="comment">*   angle     double    [deg].</span>
<a name="l00069"></a>00069 <span class="comment">*</span>
<a name="l00070"></a>00070 <span class="comment">* Function return value:</span>
<a name="l00071"></a>00071 <span class="comment">*             double    Cosine of the angle.</span>
<a name="l00072"></a>00072 <span class="comment">*</span>
<a name="l00073"></a>00073 <span class="comment">*</span>
<a name="l00074"></a>00074 <span class="comment">* sind() - Sine of an angle in degrees</span>
<a name="l00075"></a>00075 <span class="comment">* ------------------------------------</span>
<a name="l00076"></a>00076 <span class="comment">* sind() returns the sine of an angle given in degrees.</span>
<a name="l00077"></a>00077 <span class="comment">*</span>
<a name="l00078"></a>00078 <span class="comment">* Given:</span>
<a name="l00079"></a>00079 <span class="comment">*   angle     double    [deg].</span>
<a name="l00080"></a>00080 <span class="comment">*</span>
<a name="l00081"></a>00081 <span class="comment">* Function return value:</span>
<a name="l00082"></a>00082 <span class="comment">*             double    Sine of the angle.</span>
<a name="l00083"></a>00083 <span class="comment">*</span>
<a name="l00084"></a>00084 <span class="comment">*</span>
<a name="l00085"></a>00085 <span class="comment">* sincosd() - Sine and cosine of an angle in degrees</span>
<a name="l00086"></a>00086 <span class="comment">* --------------------------------------------------</span>
<a name="l00087"></a>00087 <span class="comment">* sincosd() returns the sine and cosine of an angle given in degrees.</span>
<a name="l00088"></a>00088 <span class="comment">*</span>
<a name="l00089"></a>00089 <span class="comment">* Given:</span>
<a name="l00090"></a>00090 <span class="comment">*   angle     double    [deg].</span>
<a name="l00091"></a>00091 <span class="comment">*</span>
<a name="l00092"></a>00092 <span class="comment">* Returned:</span>
<a name="l00093"></a>00093 <span class="comment">*   sin       *double   Sine of the angle.</span>
<a name="l00094"></a>00094 <span class="comment">*</span>
<a name="l00095"></a>00095 <span class="comment">*   cos       *double   Cosine of the angle.</span>
<a name="l00096"></a>00096 <span class="comment">*</span>
<a name="l00097"></a>00097 <span class="comment">* Function return value:</span>
<a name="l00098"></a>00098 <span class="comment">*             void</span>
<a name="l00099"></a>00099 <span class="comment">*</span>
<a name="l00100"></a>00100 <span class="comment">*</span>
<a name="l00101"></a>00101 <span class="comment">* tand() - Tangent of an angle in degrees</span>
<a name="l00102"></a>00102 <span class="comment">* ---------------------------------------</span>
<a name="l00103"></a>00103 <span class="comment">* tand() returns the tangent of an angle given in degrees.</span>
<a name="l00104"></a>00104 <span class="comment">*</span>
<a name="l00105"></a>00105 <span class="comment">* Given:</span>
<a name="l00106"></a>00106 <span class="comment">*   angle     double    [deg].</span>
<a name="l00107"></a>00107 <span class="comment">*</span>
<a name="l00108"></a>00108 <span class="comment">* Function return value:</span>
<a name="l00109"></a>00109 <span class="comment">*             double    Tangent of the angle.</span>
<a name="l00110"></a>00110 <span class="comment">*</span>
<a name="l00111"></a>00111 <span class="comment">*</span>
<a name="l00112"></a>00112 <span class="comment">* acosd() - Inverse cosine, returning angle in degrees</span>
<a name="l00113"></a>00113 <span class="comment">* ----------------------------------------------------</span>
<a name="l00114"></a>00114 <span class="comment">* acosd() returns the inverse cosine in degrees.</span>
<a name="l00115"></a>00115 <span class="comment">*</span>
<a name="l00116"></a>00116 <span class="comment">* Given:</span>
<a name="l00117"></a>00117 <span class="comment">*   x         double    in the range [-1,1].</span>
<a name="l00118"></a>00118 <span class="comment">*</span>
<a name="l00119"></a>00119 <span class="comment">* Function return value:</span>
<a name="l00120"></a>00120 <span class="comment">*             double    Inverse cosine of x [deg].</span>
<a name="l00121"></a>00121 <span class="comment">*</span>
<a name="l00122"></a>00122 <span class="comment">*</span>
<a name="l00123"></a>00123 <span class="comment">* asind() - Inverse sine, returning angle in degrees</span>
<a name="l00124"></a>00124 <span class="comment">* --------------------------------------------------</span>
<a name="l00125"></a>00125 <span class="comment">* asind() returns the inverse sine in degrees.</span>
<a name="l00126"></a>00126 <span class="comment">*</span>
<a name="l00127"></a>00127 <span class="comment">* Given:</span>
<a name="l00128"></a>00128 <span class="comment">*   y         double    in the range [-1,1].</span>
<a name="l00129"></a>00129 <span class="comment">*</span>
<a name="l00130"></a>00130 <span class="comment">* Function return value:</span>
<a name="l00131"></a>00131 <span class="comment">*             double    Inverse sine of y [deg].</span>
<a name="l00132"></a>00132 <span class="comment">*</span>
<a name="l00133"></a>00133 <span class="comment">*</span>
<a name="l00134"></a>00134 <span class="comment">* atand() - Inverse tangent, returning angle in degrees</span>
<a name="l00135"></a>00135 <span class="comment">* -----------------------------------------------------</span>
<a name="l00136"></a>00136 <span class="comment">* atand() returns the inverse tangent in degrees.</span>
<a name="l00137"></a>00137 <span class="comment">*</span>
<a name="l00138"></a>00138 <span class="comment">* Given:</span>
<a name="l00139"></a>00139 <span class="comment">*   s         double</span>
<a name="l00140"></a>00140 <span class="comment">*</span>
<a name="l00141"></a>00141 <span class="comment">* Function return value:</span>
<a name="l00142"></a>00142 <span class="comment">*             double    Inverse tangent of s [deg].</span>
<a name="l00143"></a>00143 <span class="comment">*</span>
<a name="l00144"></a>00144 <span class="comment">*</span>
<a name="l00145"></a>00145 <span class="comment">* atan2d() - Polar angle of (x,y), in degrees</span>
<a name="l00146"></a>00146 <span class="comment">* -------------------------------------------</span>
<a name="l00147"></a>00147 <span class="comment">* atan2d() returns the polar angle, beta, in degrees, of polar coordinates</span>
<a name="l00148"></a>00148 <span class="comment">* (rho,beta) corresponding Cartesian coordinates (x,y).  It is equivalent to</span>
<a name="l00149"></a>00149 <span class="comment">* the arg(x,y) function of WCS Paper II, though with transposed arguments.</span>
<a name="l00150"></a>00150 <span class="comment">*</span>
<a name="l00151"></a>00151 <span class="comment">* Given:</span>
<a name="l00152"></a>00152 <span class="comment">*   y         double    Cartesian y-coordinate.</span>
<a name="l00153"></a>00153 <span class="comment">*</span>
<a name="l00154"></a>00154 <span class="comment">*   x         double    Cartesian x-coordinate.</span>
<a name="l00155"></a>00155 <span class="comment">*</span>
<a name="l00156"></a>00156 <span class="comment">* Function return value:</span>
<a name="l00157"></a>00157 <span class="comment">*             double    Polar angle of (x,y) [deg].</span>
<a name="l00158"></a>00158 <span class="comment">*</span>
<a name="l00159"></a>00159 <span class="comment">*===========================================================================*/</span>
<a name="l00160"></a>00160 
<a name="l00161"></a>00161 <span class="preprocessor">#ifndef WCSLIB_WCSTRIG</span>
<a name="l00162"></a>00162 <span class="preprocessor"></span><span class="preprocessor">#define WCSLIB_WCSTRIG</span>
<a name="l00163"></a>00163 <span class="preprocessor"></span>
<a name="l00164"></a>00164 <span class="preprocessor">#include &lt;math.h&gt;</span>
<a name="l00165"></a>00165 
<a name="l00166"></a>00166 <span class="preprocessor">#include "wcsconfig.h"</span>
<a name="l00167"></a>00167 
<a name="l00168"></a>00168 <span class="preprocessor">#ifdef HAVE_SINCOS</span>
<a name="l00169"></a>00169 <span class="preprocessor"></span>  <span class="keywordtype">void</span> sincos(<span class="keywordtype">double</span> angle, <span class="keywordtype">double</span> *sin, <span class="keywordtype">double</span> *cos);
<a name="l00170"></a>00170 <span class="preprocessor">#endif</span>
<a name="l00171"></a>00171 <span class="preprocessor"></span>
<a name="l00172"></a>00172 <span class="preprocessor">#ifdef __cplusplus</span>
<a name="l00173"></a>00173 <span class="preprocessor"></span><span class="keyword">extern</span> <span class="stringliteral">"C"</span> {
<a name="l00174"></a>00174 <span class="preprocessor">#endif</span>
<a name="l00175"></a>00175 <span class="preprocessor"></span>
<a name="l00176"></a>00176 
<a name="l00177"></a>00177 <span class="preprocessor">#ifdef WCSTRIG_MACRO</span>
<a name="l00178"></a>00178 <span class="preprocessor"></span>
<a name="l00179"></a>00179 <span class="comment">/* Macro implementation of the trigd functions. */</span>
<a name="l00180"></a>00180 <span class="preprocessor">#include "<a class="code" href="wcsmath_8h.html">wcsmath.h</a>"</span>
<a name="l00181"></a>00181 
<a name="l00182"></a>00182 <span class="preprocessor">#define cosd(X) cos((X)*D2R)</span>
<a name="l00183"></a>00183 <span class="preprocessor"></span><span class="preprocessor">#define sind(X) sin((X)*D2R)</span>
<a name="l00184"></a>00184 <span class="preprocessor"></span><span class="preprocessor">#define tand(X) tan((X)*D2R)</span>
<a name="l00185"></a>00185 <span class="preprocessor"></span><span class="preprocessor">#define acosd(X) acos(X)*R2D</span>
<a name="l00186"></a>00186 <span class="preprocessor"></span><span class="preprocessor">#define asind(X) asin(X)*R2D</span>
<a name="l00187"></a>00187 <span class="preprocessor"></span><span class="preprocessor">#define atand(X) atan(X)*R2D</span>
<a name="l00188"></a>00188 <span class="preprocessor"></span><span class="preprocessor">#define atan2d(Y,X) atan2(Y,X)*R2D</span>
<a name="l00189"></a>00189 <span class="preprocessor"></span><span class="preprocessor">#ifdef HAVE_SINCOS</span>
<a name="l00190"></a>00190 <span class="preprocessor"></span><span class="preprocessor">  #define sincosd(X,S,C) sincos((X)*D2R,(S),(C))</span>
<a name="l00191"></a>00191 <span class="preprocessor"></span><span class="preprocessor">#else</span>
<a name="l00192"></a>00192 <span class="preprocessor"></span><span class="preprocessor">  #define sincosd(X,S,C) *(S) = sin((X)*D2R); *(C) = cos((X)*D2R);</span>
<a name="l00193"></a>00193 <span class="preprocessor"></span><span class="preprocessor">#endif</span>
<a name="l00194"></a>00194 <span class="preprocessor"></span>
<a name="l00195"></a>00195 <span class="preprocessor">#else</span>
<a name="l00196"></a>00196 <span class="preprocessor"></span>
<a name="l00197"></a>00197 <span class="comment">/* Use WCSLIB wrappers or native trigd functions. */</span>
<a name="l00198"></a>00198 
<a name="l00199"></a>00199 <span class="keywordtype">double</span> <a class="code" href="wcstrig_8h.html#42ae26d339f06986ca7f12ba02abcd32" title="Cosine of an angle in degrees.">cosd</a>(<span class="keywordtype">double</span> angle);
<a name="l00200"></a>00200 <span class="keywordtype">double</span> <a class="code" href="wcstrig_8h.html#2b83ceb814c90ebfa042a26d884ac159" title="Sine of an angle in degrees.">sind</a>(<span class="keywordtype">double</span> angle);
<a name="l00201"></a>00201 <span class="keywordtype">void</span> <a class="code" href="wcstrig_8h.html#ee847369fa66666bfe1e72e7872499b6" title="Sine and cosine of an angle in degrees.">sincosd</a>(<span class="keywordtype">double</span> angle, <span class="keywordtype">double</span> *sin, <span class="keywordtype">double</span> *cos);
<a name="l00202"></a>00202 <span class="keywordtype">double</span> <a class="code" href="wcstrig_8h.html#666bbac788099d5bc6d88e685f2713a3" title="Tangent of an angle in degrees.">tand</a>(<span class="keywordtype">double</span> angle);
<a name="l00203"></a>00203 <span class="keywordtype">double</span> <a class="code" href="wcstrig_8h.html#b4e520246350c50275f899c9b97c68d3" title="Inverse cosine, returning angle in degrees.">acosd</a>(<span class="keywordtype">double</span> x);
<a name="l00204"></a>00204 <span class="keywordtype">double</span> <a class="code" href="wcstrig_8h.html#7a2ae59365f19adb4af90f4df3074e50" title="Inverse sine, returning angle in degrees.">asind</a>(<span class="keywordtype">double</span> y);
<a name="l00205"></a>00205 <span class="keywordtype">double</span> <a class="code" href="wcstrig_8h.html#872bdab5707df527946ecbad24ee03ab" title="Inverse tangent, returning angle in degrees.">atand</a>(<span class="keywordtype">double</span> s);
<a name="l00206"></a>00206 <span class="keywordtype">double</span> <a class="code" href="wcstrig_8h.html#d029e98723548c7236e805c7b48c7c90" title="Polar angle of , in degrees.">atan2d</a>(<span class="keywordtype">double</span> y, <span class="keywordtype">double</span> x);
<a name="l00207"></a>00207 
<a name="l00208"></a>00208 <span class="comment">/* Domain tolerance for asin() and acos() functions. */</span>
<a name="l00209"></a><a class="code" href="wcstrig_8h.html#dd1b8466211aa6885bed0619f32b35c7">00209</a> <span class="preprocessor">#define WCSTRIG_TOL 1e-10</span>
<a name="l00210"></a>00210 <span class="preprocessor"></span>
<a name="l00211"></a>00211 <span class="preprocessor">#endif </span><span class="comment">/* WCSTRIG_MACRO */</span>
<a name="l00212"></a>00212 
<a name="l00213"></a>00213 
<a name="l00214"></a>00214 <span class="preprocessor">#ifdef __cplusplus</span>
<a name="l00215"></a>00215 <span class="preprocessor"></span>}
<a name="l00216"></a>00216 <span class="preprocessor">#endif</span>
<a name="l00217"></a>00217 <span class="preprocessor"></span>
<a name="l00218"></a>00218 <span class="preprocessor">#endif </span><span class="comment">/* WCSLIB_WCSTRIG */</span>
</pre></div></div>
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