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<a href="sph_8h.html">Go to the documentation of this file.</a><div class="fragment"><div class="line"><a name="l00001"></a><span class="lineno"> 1</span> <span class="comment">/*============================================================================</span></div>
<div class="line"><a name="l00002"></a><span class="lineno"> 2</span> <span class="comment"></span></div>
<div class="line"><a name="l00003"></a><span class="lineno"> 3</span> <span class="comment"> WCSLIB 4.18 - an implementation of the FITS WCS standard.</span></div>
<div class="line"><a name="l00004"></a><span class="lineno"> 4</span> <span class="comment"> Copyright (C) 1995-2013, Mark Calabretta</span></div>
<div class="line"><a name="l00005"></a><span class="lineno"> 5</span> <span class="comment"></span></div>
<div class="line"><a name="l00006"></a><span class="lineno"> 6</span> <span class="comment"> This file is part of WCSLIB.</span></div>
<div class="line"><a name="l00007"></a><span class="lineno"> 7</span> <span class="comment"></span></div>
<div class="line"><a name="l00008"></a><span class="lineno"> 8</span> <span class="comment"> WCSLIB is free software: you can redistribute it and/or modify it under the</span></div>
<div class="line"><a name="l00009"></a><span class="lineno"> 9</span> <span class="comment"> terms of the GNU Lesser General Public License as published by the Free</span></div>
<div class="line"><a name="l00010"></a><span class="lineno"> 10</span> <span class="comment"> Software Foundation, either version 3 of the License, or (at your option)</span></div>
<div class="line"><a name="l00011"></a><span class="lineno"> 11</span> <span class="comment"> any later version.</span></div>
<div class="line"><a name="l00012"></a><span class="lineno"> 12</span> <span class="comment"></span></div>
<div class="line"><a name="l00013"></a><span class="lineno"> 13</span> <span class="comment"> WCSLIB is distributed in the hope that it will be useful, but WITHOUT ANY</span></div>
<div class="line"><a name="l00014"></a><span class="lineno"> 14</span> <span class="comment"> WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS</span></div>
<div class="line"><a name="l00015"></a><span class="lineno"> 15</span> <span class="comment"> FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for</span></div>
<div class="line"><a name="l00016"></a><span class="lineno"> 16</span> <span class="comment"> more details.</span></div>
<div class="line"><a name="l00017"></a><span class="lineno"> 17</span> <span class="comment"></span></div>
<div class="line"><a name="l00018"></a><span class="lineno"> 18</span> <span class="comment"> You should have received a copy of the GNU Lesser General Public License</span></div>
<div class="line"><a name="l00019"></a><span class="lineno"> 19</span> <span class="comment"> along with WCSLIB. If not, see http://www.gnu.org/licenses.</span></div>
<div class="line"><a name="l00020"></a><span class="lineno"> 20</span> <span class="comment"></span></div>
<div class="line"><a name="l00021"></a><span class="lineno"> 21</span> <span class="comment"> Direct correspondence concerning WCSLIB to mark@calabretta.id.au</span></div>
<div class="line"><a name="l00022"></a><span class="lineno"> 22</span> <span class="comment"></span></div>
<div class="line"><a name="l00023"></a><span class="lineno"> 23</span> <span class="comment"> Author: Mark Calabretta, Australia Telescope National Facility, CSIRO.</span></div>
<div class="line"><a name="l00024"></a><span class="lineno"> 24</span> <span class="comment"> http://www.atnf.csiro.au/people/Mark.Calabretta</span></div>
<div class="line"><a name="l00025"></a><span class="lineno"> 25</span> <span class="comment"> $Id: sph.h,v 4.18 2013/07/13 10:00:04 mcalabre Exp $</span></div>
<div class="line"><a name="l00026"></a><span class="lineno"> 26</span> <span class="comment">*=============================================================================</span></div>
<div class="line"><a name="l00027"></a><span class="lineno"> 27</span> <span class="comment">*</span></div>
<div class="line"><a name="l00028"></a><span class="lineno"> 28</span> <span class="comment">* WCSLIB 4.18 - C routines that implement the spherical coordinate</span></div>
<div class="line"><a name="l00029"></a><span class="lineno"> 29</span> <span class="comment">* transformations used by the FITS World Coordinate System (WCS) standard.</span></div>
<div class="line"><a name="l00030"></a><span class="lineno"> 30</span> <span class="comment">* Refer to</span></div>
<div class="line"><a name="l00031"></a><span class="lineno"> 31</span> <span class="comment">*</span></div>
<div class="line"><a name="l00032"></a><span class="lineno"> 32</span> <span class="comment">* "Representations of world coordinates in FITS",</span></div>
<div class="line"><a name="l00033"></a><span class="lineno"> 33</span> <span class="comment">* Greisen, E.W., & Calabretta, M.R. 2002, A&A, 395, 1061 (Paper I)</span></div>
<div class="line"><a name="l00034"></a><span class="lineno"> 34</span> <span class="comment">*</span></div>
<div class="line"><a name="l00035"></a><span class="lineno"> 35</span> <span class="comment">* "Representations of celestial coordinates in FITS",</span></div>
<div class="line"><a name="l00036"></a><span class="lineno"> 36</span> <span class="comment">* Calabretta, M.R., & Greisen, E.W. 2002, A&A, 395, 1077 (Paper II)</span></div>
<div class="line"><a name="l00037"></a><span class="lineno"> 37</span> <span class="comment">*</span></div>
<div class="line"><a name="l00038"></a><span class="lineno"> 38</span> <span class="comment">* Refer to the README file provided with WCSLIB for an overview of the</span></div>
<div class="line"><a name="l00039"></a><span class="lineno"> 39</span> <span class="comment">* library.</span></div>
<div class="line"><a name="l00040"></a><span class="lineno"> 40</span> <span class="comment">*</span></div>
<div class="line"><a name="l00041"></a><span class="lineno"> 41</span> <span class="comment">*</span></div>
<div class="line"><a name="l00042"></a><span class="lineno"> 42</span> <span class="comment">* Summary of the sph routines</span></div>
<div class="line"><a name="l00043"></a><span class="lineno"> 43</span> <span class="comment">* ---------------------------</span></div>
<div class="line"><a name="l00044"></a><span class="lineno"> 44</span> <span class="comment">* The WCS spherical coordinate transformations are implemented via separate</span></div>
<div class="line"><a name="l00045"></a><span class="lineno"> 45</span> <span class="comment">* functions, sphx2s() and sphs2x(), for the transformation in each direction.</span></div>
<div class="line"><a name="l00046"></a><span class="lineno"> 46</span> <span class="comment">*</span></div>
<div class="line"><a name="l00047"></a><span class="lineno"> 47</span> <span class="comment">* A utility function, sphdpa(), computes the angular distances and position</span></div>
<div class="line"><a name="l00048"></a><span class="lineno"> 48</span> <span class="comment">* angles from a given point on the sky to a number of other points. sphpad()</span></div>
<div class="line"><a name="l00049"></a><span class="lineno"> 49</span> <span class="comment">* does the complementary operation - computes the coordinates of points offset</span></div>
<div class="line"><a name="l00050"></a><span class="lineno"> 50</span> <span class="comment">* by the given angular distances and position angles from a given point on the</span></div>
<div class="line"><a name="l00051"></a><span class="lineno"> 51</span> <span class="comment">* sky.</span></div>
<div class="line"><a name="l00052"></a><span class="lineno"> 52</span> <span class="comment">*</span></div>
<div class="line"><a name="l00053"></a><span class="lineno"> 53</span> <span class="comment">*</span></div>
<div class="line"><a name="l00054"></a><span class="lineno"> 54</span> <span class="comment">* sphx2s() - Rotation in the pixel-to-world direction</span></div>
<div class="line"><a name="l00055"></a><span class="lineno"> 55</span> <span class="comment">* ---------------------------------------------------</span></div>
<div class="line"><a name="l00056"></a><span class="lineno"> 56</span> <span class="comment">* sphx2s() transforms native coordinates of a projection to celestial</span></div>
<div class="line"><a name="l00057"></a><span class="lineno"> 57</span> <span class="comment">* coordinates.</span></div>
<div class="line"><a name="l00058"></a><span class="lineno"> 58</span> <span class="comment">*</span></div>
<div class="line"><a name="l00059"></a><span class="lineno"> 59</span> <span class="comment">* Given:</span></div>
<div class="line"><a name="l00060"></a><span class="lineno"> 60</span> <span class="comment">* eul const double[5]</span></div>
<div class="line"><a name="l00061"></a><span class="lineno"> 61</span> <span class="comment">* Euler angles for the transformation:</span></div>
<div class="line"><a name="l00062"></a><span class="lineno"> 62</span> <span class="comment">* 0: Celestial longitude of the native pole [deg].</span></div>
<div class="line"><a name="l00063"></a><span class="lineno"> 63</span> <span class="comment">* 1: Celestial colatitude of the native pole, or</span></div>
<div class="line"><a name="l00064"></a><span class="lineno"> 64</span> <span class="comment">* native colatitude of the celestial pole [deg].</span></div>
<div class="line"><a name="l00065"></a><span class="lineno"> 65</span> <span class="comment">* 2: Native longitude of the celestial pole [deg].</span></div>
<div class="line"><a name="l00066"></a><span class="lineno"> 66</span> <span class="comment">* 3: cos(eul[1])</span></div>
<div class="line"><a name="l00067"></a><span class="lineno"> 67</span> <span class="comment">* 4: sin(eul[1])</span></div>
<div class="line"><a name="l00068"></a><span class="lineno"> 68</span> <span class="comment">*</span></div>
<div class="line"><a name="l00069"></a><span class="lineno"> 69</span> <span class="comment">* nphi,</span></div>
<div class="line"><a name="l00070"></a><span class="lineno"> 70</span> <span class="comment">* ntheta int Vector lengths.</span></div>
<div class="line"><a name="l00071"></a><span class="lineno"> 71</span> <span class="comment">*</span></div>
<div class="line"><a name="l00072"></a><span class="lineno"> 72</span> <span class="comment">* spt,sxy int Vector strides.</span></div>
<div class="line"><a name="l00073"></a><span class="lineno"> 73</span> <span class="comment">*</span></div>
<div class="line"><a name="l00074"></a><span class="lineno"> 74</span> <span class="comment">* phi,theta const double[]</span></div>
<div class="line"><a name="l00075"></a><span class="lineno"> 75</span> <span class="comment">* Longitude and latitude in the native coordinate</span></div>
<div class="line"><a name="l00076"></a><span class="lineno"> 76</span> <span class="comment">* system of the projection [deg].</span></div>
<div class="line"><a name="l00077"></a><span class="lineno"> 77</span> <span class="comment">*</span></div>
<div class="line"><a name="l00078"></a><span class="lineno"> 78</span> <span class="comment">* Returned:</span></div>
<div class="line"><a name="l00079"></a><span class="lineno"> 79</span> <span class="comment">* lng,lat double[] Celestial longitude and latitude [deg]. These may</span></div>
<div class="line"><a name="l00080"></a><span class="lineno"> 80</span> <span class="comment">* refer to the same storage as phi and theta</span></div>
<div class="line"><a name="l00081"></a><span class="lineno"> 81</span> <span class="comment">* respectively.</span></div>
<div class="line"><a name="l00082"></a><span class="lineno"> 82</span> <span class="comment">*</span></div>
<div class="line"><a name="l00083"></a><span class="lineno"> 83</span> <span class="comment">* Function return value:</span></div>
<div class="line"><a name="l00084"></a><span class="lineno"> 84</span> <span class="comment">* int Status return value:</span></div>
<div class="line"><a name="l00085"></a><span class="lineno"> 85</span> <span class="comment">* 0: Success.</span></div>
<div class="line"><a name="l00086"></a><span class="lineno"> 86</span> <span class="comment">*</span></div>
<div class="line"><a name="l00087"></a><span class="lineno"> 87</span> <span class="comment">*</span></div>
<div class="line"><a name="l00088"></a><span class="lineno"> 88</span> <span class="comment">* sphs2x() - Rotation in the world-to-pixel direction</span></div>
<div class="line"><a name="l00089"></a><span class="lineno"> 89</span> <span class="comment">* ---------------------------------------------------</span></div>
<div class="line"><a name="l00090"></a><span class="lineno"> 90</span> <span class="comment">* sphs2x() transforms celestial coordinates to the native coordinates of a</span></div>
<div class="line"><a name="l00091"></a><span class="lineno"> 91</span> <span class="comment">* projection.</span></div>
<div class="line"><a name="l00092"></a><span class="lineno"> 92</span> <span class="comment">*</span></div>
<div class="line"><a name="l00093"></a><span class="lineno"> 93</span> <span class="comment">* Given:</span></div>
<div class="line"><a name="l00094"></a><span class="lineno"> 94</span> <span class="comment">* eul const double[5]</span></div>
<div class="line"><a name="l00095"></a><span class="lineno"> 95</span> <span class="comment">* Euler angles for the transformation:</span></div>
<div class="line"><a name="l00096"></a><span class="lineno"> 96</span> <span class="comment">* 0: Celestial longitude of the native pole [deg].</span></div>
<div class="line"><a name="l00097"></a><span class="lineno"> 97</span> <span class="comment">* 1: Celestial colatitude of the native pole, or</span></div>
<div class="line"><a name="l00098"></a><span class="lineno"> 98</span> <span class="comment">* native colatitude of the celestial pole [deg].</span></div>
<div class="line"><a name="l00099"></a><span class="lineno"> 99</span> <span class="comment">* 2: Native longitude of the celestial pole [deg].</span></div>
<div class="line"><a name="l00100"></a><span class="lineno"> 100</span> <span class="comment">* 3: cos(eul[1])</span></div>
<div class="line"><a name="l00101"></a><span class="lineno"> 101</span> <span class="comment">* 4: sin(eul[1])</span></div>
<div class="line"><a name="l00102"></a><span class="lineno"> 102</span> <span class="comment">*</span></div>
<div class="line"><a name="l00103"></a><span class="lineno"> 103</span> <span class="comment">* nlng,nlat int Vector lengths.</span></div>
<div class="line"><a name="l00104"></a><span class="lineno"> 104</span> <span class="comment">*</span></div>
<div class="line"><a name="l00105"></a><span class="lineno"> 105</span> <span class="comment">* sll,spt int Vector strides.</span></div>
<div class="line"><a name="l00106"></a><span class="lineno"> 106</span> <span class="comment">*</span></div>
<div class="line"><a name="l00107"></a><span class="lineno"> 107</span> <span class="comment">* lng,lat const double[]</span></div>
<div class="line"><a name="l00108"></a><span class="lineno"> 108</span> <span class="comment">* Celestial longitude and latitude [deg].</span></div>
<div class="line"><a name="l00109"></a><span class="lineno"> 109</span> <span class="comment">*</span></div>
<div class="line"><a name="l00110"></a><span class="lineno"> 110</span> <span class="comment">* Returned:</span></div>
<div class="line"><a name="l00111"></a><span class="lineno"> 111</span> <span class="comment">* phi,theta double[] Longitude and latitude in the native coordinate system</span></div>
<div class="line"><a name="l00112"></a><span class="lineno"> 112</span> <span class="comment">* of the projection [deg]. These may refer to the same</span></div>
<div class="line"><a name="l00113"></a><span class="lineno"> 113</span> <span class="comment">* storage as lng and lat respectively.</span></div>
<div class="line"><a name="l00114"></a><span class="lineno"> 114</span> <span class="comment">*</span></div>
<div class="line"><a name="l00115"></a><span class="lineno"> 115</span> <span class="comment">* Function return value:</span></div>
<div class="line"><a name="l00116"></a><span class="lineno"> 116</span> <span class="comment">* int Status return value:</span></div>
<div class="line"><a name="l00117"></a><span class="lineno"> 117</span> <span class="comment">* 0: Success.</span></div>
<div class="line"><a name="l00118"></a><span class="lineno"> 118</span> <span class="comment">*</span></div>
<div class="line"><a name="l00119"></a><span class="lineno"> 119</span> <span class="comment">*</span></div>
<div class="line"><a name="l00120"></a><span class="lineno"> 120</span> <span class="comment">* sphdpa() - Compute angular distance and position angle</span></div>
<div class="line"><a name="l00121"></a><span class="lineno"> 121</span> <span class="comment">* ------------------------------------------------------</span></div>
<div class="line"><a name="l00122"></a><span class="lineno"> 122</span> <span class="comment">* sphdpa() computes the angular distance and generalized position angle (see</span></div>
<div class="line"><a name="l00123"></a><span class="lineno"> 123</span> <span class="comment">* notes) from a "reference" point to a number of "field" points on the sphere.</span></div>
<div class="line"><a name="l00124"></a><span class="lineno"> 124</span> <span class="comment">* The points must be specified consistently in any spherical coordinate</span></div>
<div class="line"><a name="l00125"></a><span class="lineno"> 125</span> <span class="comment">* system.</span></div>
<div class="line"><a name="l00126"></a><span class="lineno"> 126</span> <span class="comment">*</span></div>
<div class="line"><a name="l00127"></a><span class="lineno"> 127</span> <span class="comment">* sphdpa() is complementary to sphpad().</span></div>
<div class="line"><a name="l00128"></a><span class="lineno"> 128</span> <span class="comment">*</span></div>
<div class="line"><a name="l00129"></a><span class="lineno"> 129</span> <span class="comment">* Given:</span></div>
<div class="line"><a name="l00130"></a><span class="lineno"> 130</span> <span class="comment">* nfield int The number of field points.</span></div>
<div class="line"><a name="l00131"></a><span class="lineno"> 131</span> <span class="comment">*</span></div>
<div class="line"><a name="l00132"></a><span class="lineno"> 132</span> <span class="comment">* lng0,lat0 double Spherical coordinates of the reference point [deg].</span></div>
<div class="line"><a name="l00133"></a><span class="lineno"> 133</span> <span class="comment">*</span></div>
<div class="line"><a name="l00134"></a><span class="lineno"> 134</span> <span class="comment">* lng,lat const double[]</span></div>
<div class="line"><a name="l00135"></a><span class="lineno"> 135</span> <span class="comment">* Spherical coordinates of the field points [deg].</span></div>
<div class="line"><a name="l00136"></a><span class="lineno"> 136</span> <span class="comment">*</span></div>
<div class="line"><a name="l00137"></a><span class="lineno"> 137</span> <span class="comment">* Returned:</span></div>
<div class="line"><a name="l00138"></a><span class="lineno"> 138</span> <span class="comment">* dist,pa double[] Angular distances and position angles [deg]. These</span></div>
<div class="line"><a name="l00139"></a><span class="lineno"> 139</span> <span class="comment">* may refer to the same storage as lng and lat</span></div>
<div class="line"><a name="l00140"></a><span class="lineno"> 140</span> <span class="comment">* respectively.</span></div>
<div class="line"><a name="l00141"></a><span class="lineno"> 141</span> <span class="comment">*</span></div>
<div class="line"><a name="l00142"></a><span class="lineno"> 142</span> <span class="comment">* Function return value:</span></div>
<div class="line"><a name="l00143"></a><span class="lineno"> 143</span> <span class="comment">* int Status return value:</span></div>
<div class="line"><a name="l00144"></a><span class="lineno"> 144</span> <span class="comment">* 0: Success.</span></div>
<div class="line"><a name="l00145"></a><span class="lineno"> 145</span> <span class="comment">*</span></div>
<div class="line"><a name="l00146"></a><span class="lineno"> 146</span> <span class="comment">* Notes:</span></div>
<div class="line"><a name="l00147"></a><span class="lineno"> 147</span> <span class="comment">* sphdpa() uses sphs2x() to rotate coordinates so that the reference point</span></div>
<div class="line"><a name="l00148"></a><span class="lineno"> 148</span> <span class="comment">* is at the north pole of the new system with the north pole of the old</span></div>
<div class="line"><a name="l00149"></a><span class="lineno"> 149</span> <span class="comment">* system at zero longitude in the new. The Euler angles required by</span></div>
<div class="line"><a name="l00150"></a><span class="lineno"> 150</span> <span class="comment">* sphs2x() for this rotation are</span></div>
<div class="line"><a name="l00151"></a><span class="lineno"> 151</span> <span class="comment">*</span></div>
<div class="line"><a name="l00152"></a><span class="lineno"> 152</span> <span class="comment">= eul[0] = lng0;</span></div>
<div class="line"><a name="l00153"></a><span class="lineno"> 153</span> <span class="comment">= eul[1] = 90.0 - lat0;</span></div>
<div class="line"><a name="l00154"></a><span class="lineno"> 154</span> <span class="comment">= eul[2] = 0.0;</span></div>
<div class="line"><a name="l00155"></a><span class="lineno"> 155</span> <span class="comment">*</span></div>
<div class="line"><a name="l00156"></a><span class="lineno"> 156</span> <span class="comment">* The angular distance and generalized position angle are readily obtained</span></div>
<div class="line"><a name="l00157"></a><span class="lineno"> 157</span> <span class="comment">* from the longitude and latitude of the field point in the new system.</span></div>
<div class="line"><a name="l00158"></a><span class="lineno"> 158</span> <span class="comment">* This applies even if the reference point is at one of the poles, in which</span></div>
<div class="line"><a name="l00159"></a><span class="lineno"> 159</span> <span class="comment">* case the "position angle" returned is as would be computed for a reference</span></div>
<div class="line"><a name="l00160"></a><span class="lineno"> 160</span> <span class="comment">* point at (lng0,+90-epsilon) or (lng0,-90+epsilon), in the limit as epsilon</span></div>
<div class="line"><a name="l00161"></a><span class="lineno"> 161</span> <span class="comment">* goes to zero.</span></div>
<div class="line"><a name="l00162"></a><span class="lineno"> 162</span> <span class="comment">*</span></div>
<div class="line"><a name="l00163"></a><span class="lineno"> 163</span> <span class="comment">* It is evident that the coordinate system in which the two points are</span></div>
<div class="line"><a name="l00164"></a><span class="lineno"> 164</span> <span class="comment">* expressed is irrelevant to the determination of the angular separation</span></div>
<div class="line"><a name="l00165"></a><span class="lineno"> 165</span> <span class="comment">* between the points. However, this is not true of the generalized position</span></div>
<div class="line"><a name="l00166"></a><span class="lineno"> 166</span> <span class="comment">* angle.</span></div>
<div class="line"><a name="l00167"></a><span class="lineno"> 167</span> <span class="comment">*</span></div>
<div class="line"><a name="l00168"></a><span class="lineno"> 168</span> <span class="comment">* The generalized position angle is here defined as the angle of</span></div>
<div class="line"><a name="l00169"></a><span class="lineno"> 169</span> <span class="comment">* intersection of the great circle containing the reference and field points</span></div>
<div class="line"><a name="l00170"></a><span class="lineno"> 170</span> <span class="comment">* with that containing the reference point and the pole. It has its normal</span></div>
<div class="line"><a name="l00171"></a><span class="lineno"> 171</span> <span class="comment">* meaning when the the reference and field points are specified in</span></div>
<div class="line"><a name="l00172"></a><span class="lineno"> 172</span> <span class="comment">* equatorial coordinates (right ascension and declination).</span></div>
<div class="line"><a name="l00173"></a><span class="lineno"> 173</span> <span class="comment">*</span></div>
<div class="line"><a name="l00174"></a><span class="lineno"> 174</span> <span class="comment">* Interchanging the reference and field points changes the position angle in</span></div>
<div class="line"><a name="l00175"></a><span class="lineno"> 175</span> <span class="comment">* a non-intuitive way (because the sum of the angles of a spherical triangle</span></div>
<div class="line"><a name="l00176"></a><span class="lineno"> 176</span> <span class="comment">* normally exceeds 180 degrees).</span></div>
<div class="line"><a name="l00177"></a><span class="lineno"> 177</span> <span class="comment">*</span></div>
<div class="line"><a name="l00178"></a><span class="lineno"> 178</span> <span class="comment">* The position angle is undefined if the reference and field points are</span></div>
<div class="line"><a name="l00179"></a><span class="lineno"> 179</span> <span class="comment">* coincident or antipodal. This may be detected by checking for a distance</span></div>
<div class="line"><a name="l00180"></a><span class="lineno"> 180</span> <span class="comment">* of 0 or 180 degrees (within rounding tolerance). sphdpa() will return an</span></div>
<div class="line"><a name="l00181"></a><span class="lineno"> 181</span> <span class="comment">* arbitrary position angle in such circumstances.</span></div>
<div class="line"><a name="l00182"></a><span class="lineno"> 182</span> <span class="comment">*</span></div>
<div class="line"><a name="l00183"></a><span class="lineno"> 183</span> <span class="comment">*</span></div>
<div class="line"><a name="l00184"></a><span class="lineno"> 184</span> <span class="comment">* sphpad() - Compute field points offset from a given point</span></div>
<div class="line"><a name="l00185"></a><span class="lineno"> 185</span> <span class="comment">* ---------------------------------------------------------</span></div>
<div class="line"><a name="l00186"></a><span class="lineno"> 186</span> <span class="comment">* sphpad() computes the coordinates of a set of points that are offset by the</span></div>
<div class="line"><a name="l00187"></a><span class="lineno"> 187</span> <span class="comment">* specified angular distances and position angles from a given "reference"</span></div>
<div class="line"><a name="l00188"></a><span class="lineno"> 188</span> <span class="comment">* point on the sky. The distances and position angles must be specified</span></div>
<div class="line"><a name="l00189"></a><span class="lineno"> 189</span> <span class="comment">* consistently in any spherical coordinate system.</span></div>
<div class="line"><a name="l00190"></a><span class="lineno"> 190</span> <span class="comment">*</span></div>
<div class="line"><a name="l00191"></a><span class="lineno"> 191</span> <span class="comment">* sphpad() is complementary to sphdpa().</span></div>
<div class="line"><a name="l00192"></a><span class="lineno"> 192</span> <span class="comment">*</span></div>
<div class="line"><a name="l00193"></a><span class="lineno"> 193</span> <span class="comment">* Given:</span></div>
<div class="line"><a name="l00194"></a><span class="lineno"> 194</span> <span class="comment">* nfield int The number of field points.</span></div>
<div class="line"><a name="l00195"></a><span class="lineno"> 195</span> <span class="comment">*</span></div>
<div class="line"><a name="l00196"></a><span class="lineno"> 196</span> <span class="comment">* lng0,lat0 double Spherical coordinates of the reference point [deg].</span></div>
<div class="line"><a name="l00197"></a><span class="lineno"> 197</span> <span class="comment">*</span></div>
<div class="line"><a name="l00198"></a><span class="lineno"> 198</span> <span class="comment">* dist,pa const double[]</span></div>
<div class="line"><a name="l00199"></a><span class="lineno"> 199</span> <span class="comment">* Angular distances and position angles [deg].</span></div>
<div class="line"><a name="l00200"></a><span class="lineno"> 200</span> <span class="comment">*</span></div>
<div class="line"><a name="l00201"></a><span class="lineno"> 201</span> <span class="comment">* Returned:</span></div>
<div class="line"><a name="l00202"></a><span class="lineno"> 202</span> <span class="comment">* lng,lat double[] Spherical coordinates of the field points [deg].</span></div>
<div class="line"><a name="l00203"></a><span class="lineno"> 203</span> <span class="comment">* These may refer to the same storage as dist and pa</span></div>
<div class="line"><a name="l00204"></a><span class="lineno"> 204</span> <span class="comment">* respectively.</span></div>
<div class="line"><a name="l00205"></a><span class="lineno"> 205</span> <span class="comment">*</span></div>
<div class="line"><a name="l00206"></a><span class="lineno"> 206</span> <span class="comment">* Function return value:</span></div>
<div class="line"><a name="l00207"></a><span class="lineno"> 207</span> <span class="comment">* int Status return value:</span></div>
<div class="line"><a name="l00208"></a><span class="lineno"> 208</span> <span class="comment">* 0: Success.</span></div>
<div class="line"><a name="l00209"></a><span class="lineno"> 209</span> <span class="comment">*</span></div>
<div class="line"><a name="l00210"></a><span class="lineno"> 210</span> <span class="comment">* Notes:</span></div>
<div class="line"><a name="l00211"></a><span class="lineno"> 211</span> <span class="comment">* sphpad() is implemented analogously to sphdpa() although using sphx2s()</span></div>
<div class="line"><a name="l00212"></a><span class="lineno"> 212</span> <span class="comment">* for the inverse transformation. In particular, when the reference point</span></div>
<div class="line"><a name="l00213"></a><span class="lineno"> 213</span> <span class="comment">* is at one of the poles, "position angle" is interpreted as though the</span></div>
<div class="line"><a name="l00214"></a><span class="lineno"> 214</span> <span class="comment">* reference point was at (lng0,+90-epsilon) or (lng0,-90+epsilon), in the</span></div>
<div class="line"><a name="l00215"></a><span class="lineno"> 215</span> <span class="comment">* limit as epsilon goes to zero.</span></div>
<div class="line"><a name="l00216"></a><span class="lineno"> 216</span> <span class="comment">*</span></div>
<div class="line"><a name="l00217"></a><span class="lineno"> 217</span> <span class="comment">* Applying sphpad() with the distances and position angles computed by</span></div>
<div class="line"><a name="l00218"></a><span class="lineno"> 218</span> <span class="comment">* sphdpa() should return the original field points.</span></div>
<div class="line"><a name="l00219"></a><span class="lineno"> 219</span> <span class="comment">*</span></div>
<div class="line"><a name="l00220"></a><span class="lineno"> 220</span> <span class="comment">*===========================================================================*/</span></div>
<div class="line"><a name="l00221"></a><span class="lineno"> 221</span> </div>
<div class="line"><a name="l00222"></a><span class="lineno"> 222</span> <span class="preprocessor">#ifndef WCSLIB_SPH</span></div>
<div class="line"><a name="l00223"></a><span class="lineno"> 223</span> <span class="preprocessor"></span><span class="preprocessor">#define WCSLIB_SPH</span></div>
<div class="line"><a name="l00224"></a><span class="lineno"> 224</span> <span class="preprocessor"></span></div>
<div class="line"><a name="l00225"></a><span class="lineno"> 225</span> <span class="preprocessor">#ifdef __cplusplus</span></div>
<div class="line"><a name="l00226"></a><span class="lineno"> 226</span> <span class="preprocessor"></span><span class="keyword">extern</span> <span class="stringliteral">"C"</span> {</div>
<div class="line"><a name="l00227"></a><span class="lineno"> 227</span> <span class="preprocessor">#endif</span></div>
<div class="line"><a name="l00228"></a><span class="lineno"> 228</span> <span class="preprocessor"></span></div>
<div class="line"><a name="l00229"></a><span class="lineno"> 229</span> </div>
<div class="line"><a name="l00230"></a><span class="lineno"> 230</span> <span class="keywordtype">int</span> <a class="code" href="sph_8h.html#abcdbd119e57482315882d849f2b04e91" title="Rotation in the pixel-to-world direction. ">sphx2s</a>(<span class="keyword">const</span> <span class="keywordtype">double</span> eul[5], <span class="keywordtype">int</span> nphi, <span class="keywordtype">int</span> ntheta, <span class="keywordtype">int</span> spt, <span class="keywordtype">int</span> sxy,</div>
<div class="line"><a name="l00231"></a><span class="lineno"> 231</span>  <span class="keyword">const</span> <span class="keywordtype">double</span> phi[], <span class="keyword">const</span> <span class="keywordtype">double</span> theta[],</div>
<div class="line"><a name="l00232"></a><span class="lineno"> 232</span>  <span class="keywordtype">double</span> lng[], <span class="keywordtype">double</span> lat[]);</div>
<div class="line"><a name="l00233"></a><span class="lineno"> 233</span> </div>
<div class="line"><a name="l00234"></a><span class="lineno"> 234</span> <span class="keywordtype">int</span> <a class="code" href="sph_8h.html#a5c0783d56189d48d9f52af05b64a4df6" title="Rotation in the world-to-pixel direction. ">sphs2x</a>(<span class="keyword">const</span> <span class="keywordtype">double</span> eul[5], <span class="keywordtype">int</span> nlng, <span class="keywordtype">int</span> nlat, <span class="keywordtype">int</span> sll , <span class="keywordtype">int</span> spt,</div>
<div class="line"><a name="l00235"></a><span class="lineno"> 235</span>  <span class="keyword">const</span> <span class="keywordtype">double</span> lng[], <span class="keyword">const</span> <span class="keywordtype">double</span> lat[],</div>
<div class="line"><a name="l00236"></a><span class="lineno"> 236</span>  <span class="keywordtype">double</span> phi[], <span class="keywordtype">double</span> theta[]);</div>
<div class="line"><a name="l00237"></a><span class="lineno"> 237</span> </div>
<div class="line"><a name="l00238"></a><span class="lineno"> 238</span> <span class="keywordtype">int</span> <a class="code" href="sph_8h.html#aec6222fe1e4d807c9b59980b8e548eb0" title="Compute angular distance and position angle. ">sphdpa</a>(<span class="keywordtype">int</span> nfield, <span class="keywordtype">double</span> lng0, <span class="keywordtype">double</span> lat0,</div>
<div class="line"><a name="l00239"></a><span class="lineno"> 239</span>  <span class="keyword">const</span> <span class="keywordtype">double</span> lng[], <span class="keyword">const</span> <span class="keywordtype">double</span> lat[],</div>
<div class="line"><a name="l00240"></a><span class="lineno"> 240</span>  <span class="keywordtype">double</span> dist[], <span class="keywordtype">double</span> pa[]);</div>
<div class="line"><a name="l00241"></a><span class="lineno"> 241</span> </div>
<div class="line"><a name="l00242"></a><span class="lineno"> 242</span> <span class="keywordtype">int</span> <a class="code" href="sph_8h.html#a8ee2e117701f434f0bffbbe52f05d118" title="Compute field points offset from a given point. ">sphpad</a>(<span class="keywordtype">int</span> nfield, <span class="keywordtype">double</span> lng0, <span class="keywordtype">double</span> lat0,</div>
<div class="line"><a name="l00243"></a><span class="lineno"> 243</span>  <span class="keyword">const</span> <span class="keywordtype">double</span> dist[], <span class="keyword">const</span> <span class="keywordtype">double</span> pa[],</div>
<div class="line"><a name="l00244"></a><span class="lineno"> 244</span>  <span class="keywordtype">double</span> lng[], <span class="keywordtype">double</span> lat[]);</div>
<div class="line"><a name="l00245"></a><span class="lineno"> 245</span> </div>
<div class="line"><a name="l00246"></a><span class="lineno"> 246</span> </div>
<div class="line"><a name="l00247"></a><span class="lineno"> 247</span> <span class="preprocessor">#ifdef __cplusplus</span></div>
<div class="line"><a name="l00248"></a><span class="lineno"> 248</span> <span class="preprocessor"></span>}</div>
<div class="line"><a name="l00249"></a><span class="lineno"> 249</span> <span class="preprocessor">#endif</span></div>
<div class="line"><a name="l00250"></a><span class="lineno"> 250</span> <span class="preprocessor"></span></div>
<div class="line"><a name="l00251"></a><span class="lineno"> 251</span> <span class="preprocessor">#endif </span><span class="comment">/* WCSLIB_SPH */</span><span class="preprocessor"></span></div>
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