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                  <a href="#grits-grits-util.description" class="shortcut">Description</a>
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<h2><span class="refentrytitle"><a name="grits-grits-util.top_of_page"></a>grits-util</span></h2>
<p>grits-util — Geographic utilities</p>
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<a name="grits-grits-util.synopsis"></a><h2>Synopsis</h2>
<pre class="synopsis">#define             <a class="link" href="grits-grits-util.html#EARTH-C:CAPS" title="EARTH_C">EARTH_C</a>
#define             <a class="link" href="grits-grits-util.html#EARTH-R:CAPS" title="EARTH_R">EARTH_R</a>
#define             <a class="link" href="grits-grits-util.html#EAST:CAPS" title="EAST">EAST</a>
#define             <a class="link" href="grits-grits-util.html#FOV-DIST:CAPS" title="FOV_DIST">FOV_DIST</a>
struct              <a class="link" href="grits-grits-util.html#GritsBounds" title="struct GritsBounds">GritsBounds</a>;
struct              <a class="link" href="grits-grits-util.html#GritsPoint" title="struct GritsPoint">GritsPoint</a>;
#define             <a class="link" href="grits-grits-util.html#MPPX:CAPS" title="MPPX()">MPPX</a>                                (dist)
#define             <a class="link" href="grits-grits-util.html#NORTH:CAPS" title="NORTH">NORTH</a>
#define             <a class="link" href="grits-grits-util.html#SOUTH:CAPS" title="SOUTH">SOUTH</a>
#define             <a class="link" href="grits-grits-util.html#WEST:CAPS" title="WEST">WEST</a>
#define             <a class="link" href="grits-grits-util.html#azim2lon" title="azim2lon()">azim2lon</a>                            (azim)
<span class="returnvalue">void</span>                <a class="link" href="grits-grits-util.html#crossd" title="crossd ()">crossd</a>                              (<em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> *a</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> *b</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> *out</code></em>);
<span class="returnvalue">void</span>                <a class="link" href="grits-grits-util.html#crossd3" title="crossd3 ()">crossd3</a>                             (<em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> *a</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> *b</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> *c</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> *out</code></em>);
#define             <a class="link" href="grits-grits-util.html#deg2rad" title="deg2rad()">deg2rad</a>                             (deg)
<a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="returnvalue">gdouble</span></a>             <a class="link" href="grits-grits-util.html#distd" title="distd ()">distd</a>                               (<em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> *a</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> *b</code></em>);
#define             <a class="link" href="grits-grits-util.html#elev2rad" title="elev2rad()">elev2rad</a>                            (elev)
<span class="returnvalue">void</span>                <a class="link" href="grits-grits-util.html#free-points" title="free_points ()">free_points</a>                         (<em class="parameter"><code><a href="grits-grits-util.html#GritsPoint"><span class="type">GritsPoints</span></a> *points</code></em>);
<span class="returnvalue">void</span>                <a class="link" href="grits-grits-util.html#grits-bounds-set-bounds" title="grits_bounds_set_bounds ()">grits_bounds_set_bounds</a>             (<em class="parameter"><code><a class="link" href="grits-grits-util.html#GritsBounds" title="struct GritsBounds"><span class="type">GritsBounds</span></a> *bounds</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> n</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> s</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> e</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> w</code></em>);
<span class="returnvalue">void</span>                <a class="link" href="grits-grits-util.html#grits-point-set-lle" title="grits_point_set_lle ()">grits_point_set_lle</a>                 (<em class="parameter"><code><a class="link" href="grits-grits-util.html#GritsPoint" title="struct GritsPoint"><span class="type">GritsPoint</span></a> *point</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> lat</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> lon</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> elev</code></em>);
#define             <a class="link" href="grits-grits-util.html#incl2lat" title="incl2lat()">incl2lat</a>                            (incl)
#define             <a class="link" href="grits-grits-util.html#lat2incl" title="lat2incl()">lat2incl</a>                            (lat)
<a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="returnvalue">gdouble</span></a>             <a class="link" href="grits-grits-util.html#lengthd" title="lengthd ()">lengthd</a>                             (<em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> *a</code></em>);
<a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="returnvalue">gdouble</span></a>             <a class="link" href="grits-grits-util.html#ll2m" title="ll2m ()">ll2m</a>                                (<em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> lon_dist</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> lat</code></em>);
<span class="returnvalue">void</span>                <a class="link" href="grits-grits-util.html#lle2xyz" title="lle2xyz ()">lle2xyz</a>                             (<em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> lat</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> lon</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> elev</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> *x</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> *y</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> *z</code></em>);
#define             <a class="link" href="grits-grits-util.html#lon2azim" title="lon2azim()">lon2azim</a>                            (lon)
<a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="returnvalue">gdouble</span></a>             <a class="link" href="grits-grits-util.html#lon-avg" title="lon_avg ()">lon_avg</a>                             (<em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> a</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> b</code></em>);
<span class="returnvalue">void</span>                <a class="link" href="grits-grits-util.html#normd" title="normd ()">normd</a>                               (<em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> *a</code></em>);
<a href="grits-grits-util.html#GritsPoint"><span class="returnvalue">GritsPoints</span></a> *       <a class="link" href="grits-grits-util.html#parse-points" title="parse_points ()">parse_points</a>                        (<em class="parameter"><code>const <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gchar"><span class="type">gchar</span></a> *string</code></em>,
                                                         <em class="parameter"><code>const <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gchar"><span class="type">gchar</span></a> *group_sep</code></em>,
                                                         <em class="parameter"><code>const <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gchar"><span class="type">gchar</span></a> *point_sep</code></em>,
                                                         <em class="parameter"><code>const <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gchar"><span class="type">gchar</span></a> *coord_sep</code></em>,
                                                         <em class="parameter"><code><a class="link" href="grits-grits-util.html#GritsBounds" title="struct GritsBounds"><span class="type">GritsBounds</span></a> *bounds</code></em>,
                                                         <em class="parameter"><code><a class="link" href="grits-grits-util.html#GritsPoint" title="struct GritsPoint"><span class="type">GritsPoint</span></a> *center</code></em>);
#define             <a class="link" href="grits-grits-util.html#rad2deg" title="rad2deg()">rad2deg</a>                             (rad)
#define             <a class="link" href="grits-grits-util.html#rad2elev" title="rad2elev()">rad2elev</a>                            (rad)
<span class="returnvalue">void</span>                <a class="link" href="grits-grits-util.html#xyz2ll" title="xyz2ll ()">xyz2ll</a>                              (<em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> x</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> y</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> z</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> *lat</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> *lon</code></em>);
<span class="returnvalue">void</span>                <a class="link" href="grits-grits-util.html#xyz2lle" title="xyz2lle ()">xyz2lle</a>                             (<em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> x</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> y</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> z</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> *lat</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> *lon</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> *elev</code></em>);
</pre>
</div>
<div class="refsect1">
<a name="grits-grits-util.description"></a><h2>Description</h2>
<p>
Miscellaneous utility functions, these deal mostly with coordinate
conversion. Below are some examples that should help demonstrate how these
functions work.
</p>
<p>
</p>
<div class="example">
<a name="idm140346418573664"></a><p class="title"><b>Example 1. Terminology</b></p>
<div class="example-contents"><pre class="programlisting">
deg    - Degrees
rad    - Radians, also radius
m      - Meters, for earth-based distances
px     - Pixels, for screen-based distances

height - Height, the distance above the geoid (ground)
elev   - Elevation, the distance above the spheroid
rad    - Radius, the distance from the center of the earth

lat    - Latitude, amount north-south, -90 (S) .. 90 (N)
lon    - Longitude, amount east-west, -180 (W) .. 180 (E)
incl   - Inclination, polar equiv of  latitude, Pi .. 0
azim   - Azimuth, polar equiv of longitude, -Pi .. Pi

x      -  0° lon is positive
y      - 90° lon is positive
z      - North pole is positive

llh    - lat,lon,height
lle    - lat,lon,elev
llr    - lat,lon,rad
pol    - incl,azim,rad
xyz    - x,y,z
</pre></div>
</div>
<p><br class="example-break">
</p>
<p>
</p>
<div class="example">
<a name="idm140346418570896"></a><p class="title"><b>Example 2. Conversions</b></p>
<div class="example-contents"><pre class="programlisting">
            lat    lon   elev -&gt;      x      y      z
lle2xyz:    0.0,   0.0,   0.0 -&gt;    0.0,   0.0,  10.0
lle2xyz:   90.0,   0.0,   0.0 -&gt;    0.0,  10.0,   0.0
lle2xyz:    0.0,  90.0,   0.0 -&gt;   10.0,   0.0,   0.0

              x      y      z -&gt;    lat    lon   elev
xyz2lle:   10.0,   0.0,   0.0 -&gt;    0.0,  90.0,   0.0
xyz2lle:    0.0,  10.0,   0.0 -&gt;   90.0,   0.0,   0.0
xyz2lle:    0.0,   0.0,  10.0 -&gt;    0.0,   0.0,   0.0
</pre></div>
</div>
<p><br class="example-break">
</p>
</div>
<div class="refsect1">
<a name="grits-grits-util.details"></a><h2>Details</h2>
<div class="refsect2">
<a name="EARTH-C:CAPS"></a><h3>EARTH_C</h3>
<pre class="programlisting">#define EARTH_C (2*G_PI*EARTH_R)
</pre>
<p>
Circumference of the earth at the equator
</p>
</div>
<hr>
<div class="refsect2">
<a name="EARTH-R:CAPS"></a><h3>EARTH_R</h3>
<pre class="programlisting">#define EARTH_R (6371000)
</pre>
<p>
Radius of the earth
</p>
</div>
<hr>
<div class="refsect2">
<a name="EAST:CAPS"></a><h3>EAST</h3>
<pre class="programlisting">#define EAST  180
</pre>
<p>
Eastern most longitude
</p>
</div>
<hr>
<div class="refsect2">
<a name="FOV-DIST:CAPS"></a><h3>FOV_DIST</h3>
<pre class="programlisting">#define FOV_DIST   (1039.23)
</pre>
<p>
Used by GritsOpenGL to set up the drawing window
</p>
</div>
<hr>
<div class="refsect2">
<a name="GritsBounds"></a><h3>struct GritsBounds</h3>
<pre class="programlisting">struct GritsBounds {
	gdouble n, s, e, w;
};
</pre>
<p>
</p>
</div>
<hr>
<div class="refsect2">
<a name="GritsPoint"></a><h3>struct GritsPoint</h3>
<pre class="programlisting">struct GritsPoint {
	gdouble lat, lon, elev;
};
</pre>
<p>
</p>
</div>
<hr>
<div class="refsect2">
<a name="MPPX:CAPS"></a><h3>MPPX()</h3>
<pre class="programlisting">#define MPPX(dist) (dist/FOV_DIST)
</pre>
<p>
Get the resolution that a point would be drawn at on the screen
</p>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>dist</code></em> :</span></p></td>
<td>the distance between the eye and the point in question</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td>the resolution in meters per pixel</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="NORTH:CAPS"></a><h3>NORTH</h3>
<pre class="programlisting">#define NORTH  90
</pre>
<p>
Latitude at the north poll
</p>
</div>
<hr>
<div class="refsect2">
<a name="SOUTH:CAPS"></a><h3>SOUTH</h3>
<pre class="programlisting">#define SOUTH -90
</pre>
<p>
Latitude at the south poll
</p>
</div>
<hr>
<div class="refsect2">
<a name="WEST:CAPS"></a><h3>WEST</h3>
<pre class="programlisting">#define WEST -180
</pre>
<p>
Western most longitude
</p>
</div>
<hr>
<div class="refsect2">
<a name="azim2lon"></a><h3>azim2lon()</h3>
<pre class="programlisting">#define azim2lon(azim) ((azim)*180/G_PI)
</pre>
<p>
Convert azimuth to longitude
</p>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>azim</code></em> :</span></p></td>
<td>the azimuth in radians</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td>the longitude</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="crossd"></a><h3>crossd ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span>                crossd                              (<em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> *a</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> *b</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> *out</code></em>);</pre>
<p>
Calculate the cross product of two vectors
</p>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>a</code></em> :</span></p></td>
<td>the first vector</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>b</code></em> :</span></p></td>
<td>the second vector</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="crossd3"></a><h3>crossd3 ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span>                crossd3                             (<em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> *a</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> *b</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> *c</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> *out</code></em>);</pre>
<p>
Calculate the cross product of three points
</p>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>a</code></em> :</span></p></td>
<td>the left   point</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>b</code></em> :</span></p></td>
<td>the center point</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>c</code></em> :</span></p></td>
<td>the right  point</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>out</code></em> :</span></p></td>
<td>the cross product</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="deg2rad"></a><h3>deg2rad()</h3>
<pre class="programlisting">#define deg2rad(deg) (((deg)*G_PI)/180.0)
</pre>
<p>
Convert degrees to radians
</p>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>deg</code></em> :</span></p></td>
<td>the angle in degrees</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td>the angle in radians</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="distd"></a><h3>distd ()</h3>
<pre class="programlisting"><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="returnvalue">gdouble</span></a>             distd                               (<em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> *a</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> *b</code></em>);</pre>
<p>
Calculate the distance between two three dimensional points.
</p>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>a</code></em> :</span></p></td>
<td>the first point</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>b</code></em> :</span></p></td>
<td>the second point</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td>the distance between the points</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="elev2rad"></a><h3>elev2rad()</h3>
<pre class="programlisting">#define elev2rad(elev) ((elev)+EARTH_R)
</pre>
<p>
Convert elevation to radius
</p>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>elev</code></em> :</span></p></td>
<td>the elevation in meters above the earth surface</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td>the radius in meters</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="free-points"></a><h3>free_points ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span>                free_points                         (<em class="parameter"><code><a href="grits-grits-util.html#GritsPoint"><span class="type">GritsPoints</span></a> *points</code></em>);</pre>
<p>
Frees all data allocated by parse_points
</p>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody><tr>
<td><p><span class="term"><em class="parameter"><code>points</code></em> :</span></p></td>
<td>Array of points allocated by <a class="link" href="grits-grits-util.html#parse-points" title="parse_points ()"><code class="function">parse_points()</code></a>
</td>
</tr></tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="grits-bounds-set-bounds"></a><h3>grits_bounds_set_bounds ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span>                grits_bounds_set_bounds             (<em class="parameter"><code><a class="link" href="grits-grits-util.html#GritsBounds" title="struct GritsBounds"><span class="type">GritsBounds</span></a> *bounds</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> n</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> s</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> e</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> w</code></em>);</pre>
<p>
Set the north, south, east, and west edges of the bounding box
</p>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>n</code></em> :</span></p></td>
<td>the north edge</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>s</code></em> :</span></p></td>
<td>the south edge</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>e</code></em> :</span></p></td>
<td>the east edge</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>w</code></em> :</span></p></td>
<td>the west edge</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="grits-point-set-lle"></a><h3>grits_point_set_lle ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span>                grits_point_set_lle                 (<em class="parameter"><code><a class="link" href="grits-grits-util.html#GritsPoint" title="struct GritsPoint"><span class="type">GritsPoint</span></a> *point</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> lat</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> lon</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> elev</code></em>);</pre>
<p>
Set the latitude, longitude, and elevation for a point.
</p>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>point</code></em> :</span></p></td>
<td>the point to modify</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>lat</code></em> :</span></p></td>
<td>the new latitude</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>lon</code></em> :</span></p></td>
<td>the new longitude</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>elev</code></em> :</span></p></td>
<td>the new elevation</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="incl2lat"></a><h3>incl2lat()</h3>
<pre class="programlisting">#define incl2lat(incl) (90-(incl)*180/G_PI)
</pre>
<p>
Convert inclination to latitude
</p>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>incl</code></em> :</span></p></td>
<td>the inclination in radians</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td>the latitude</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="lat2incl"></a><h3>lat2incl()</h3>
<pre class="programlisting">#define lat2incl(lat)  ((90-(lat))*G_PI/180)
</pre>
<p>
Convert latitude to inclination
</p>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>lat</code></em> :</span></p></td>
<td>the latitude</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td>the inclination in radians</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="lengthd"></a><h3>lengthd ()</h3>
<pre class="programlisting"><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="returnvalue">gdouble</span></a>             lengthd                             (<em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> *a</code></em>);</pre>
<p>
Calculate the length (magnitude) of a vector.
</p>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>a</code></em> :</span></p></td>
<td>the vector</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td>the length</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="ll2m"></a><h3>ll2m ()</h3>
<pre class="programlisting"><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="returnvalue">gdouble</span></a>             ll2m                                (<em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> lon_dist</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> lat</code></em>);</pre>
<p>
Calculate the distance of longitudinal span at a particular latitude.
</p>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>lon_dist</code></em> :</span></p></td>
<td>the distance in degrees of longitude</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>lat</code></em> :</span></p></td>
<td>the latitude to calculate at</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td>the distance in meters</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="lle2xyz"></a><h3>lle2xyz ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span>                lle2xyz                             (<em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> lat</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> lon</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> elev</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> *x</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> *y</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> *z</code></em>);</pre>
<p>
Convert a point from latitude, longitude, and elevation to x, y and z
coordinates.
</p>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>lat</code></em> :</span></p></td>
<td>the latitude</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>lon</code></em> :</span></p></td>
<td>the longitude</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>elev</code></em> :</span></p></td>
<td>the elevation</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>x</code></em> :</span></p></td>
<td>the resulting x coordinate</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>y</code></em> :</span></p></td>
<td>the resulting y coordinate</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>z</code></em> :</span></p></td>
<td>the resulting z coordinate</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="lon2azim"></a><h3>lon2azim()</h3>
<pre class="programlisting">#define lon2azim(lon)  ((lon)*G_PI/180)
</pre>
<p>
Convert longitude to azimuth
</p>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>lon</code></em> :</span></p></td>
<td>the longitude</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td>the azimuth in radians</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="lon-avg"></a><h3>lon_avg ()</h3>
<pre class="programlisting"><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="returnvalue">gdouble</span></a>             lon_avg                             (<em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> a</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> b</code></em>);</pre>
<p>
Calculate the average longitude between two longitudes. This is smart about
which side of the globe the resulting longitude is placed on.
</p>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>a</code></em> :</span></p></td>
<td>the first longitude</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>b</code></em> :</span></p></td>
<td>the second longitude</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td>the average</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="normd"></a><h3>normd ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span>                normd                               (<em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> *a</code></em>);</pre>
<p>
Normalize a vector to a mangitude of 1
</p>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody><tr>
<td><p><span class="term"><em class="parameter"><code>a</code></em> :</span></p></td>
<td>the first longitude</td>
</tr></tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="parse-points"></a><h3>parse_points ()</h3>
<pre class="programlisting"><a href="grits-grits-util.html#GritsPoint"><span class="returnvalue">GritsPoints</span></a> *       parse_points                        (<em class="parameter"><code>const <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gchar"><span class="type">gchar</span></a> *string</code></em>,
                                                         <em class="parameter"><code>const <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gchar"><span class="type">gchar</span></a> *group_sep</code></em>,
                                                         <em class="parameter"><code>const <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gchar"><span class="type">gchar</span></a> *point_sep</code></em>,
                                                         <em class="parameter"><code>const <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gchar"><span class="type">gchar</span></a> *coord_sep</code></em>,
                                                         <em class="parameter"><code><a class="link" href="grits-grits-util.html#GritsBounds" title="struct GritsBounds"><span class="type">GritsBounds</span></a> *bounds</code></em>,
                                                         <em class="parameter"><code><a class="link" href="grits-grits-util.html#GritsPoint" title="struct GritsPoint"><span class="type">GritsPoint</span></a> *center</code></em>);</pre>
<p>
Parse a string of the form:
  string -&gt; group [<em class="parameter"><code>group_sep</code></em> group] ...
  group  -&gt; point [<em class="parameter"><code>point_sep</code></em> point] ...
  point  -&gt; latitude <em class="parameter"><code>coord_sep</code></em> longitude [<em class="parameter"><code>coord_sep</code></em> elevation]
</p>
<p>
For example
  parse_points("30,-80 30,-120 50,-120 50,-80", "\t", " ", ",");
</p>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>string</code></em> :</span></p></td>
<td>String representation of the points</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>group_sep</code></em> :</span></p></td>
<td>Group separator</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>point_sep</code></em> :</span></p></td>
<td>Point separator</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>coord_sep</code></em> :</span></p></td>
<td>Coordinate separator</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>bounds</code></em> :</span></p></td>
<td>The bounding box of all the points, or NULL</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>center</code></em> :</span></p></td>
<td>The center of the <em class="parameter"><code>bounds</code></em>, or NULL</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td>zero-terminated array of groups of points</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="rad2deg"></a><h3>rad2deg()</h3>
<pre class="programlisting">#define rad2deg(rad) (((rad)*180.0)/G_PI)
</pre>
<p>
Convert radians to degrees
</p>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>rad</code></em> :</span></p></td>
<td>the angle in radians</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td>the angle in degrees</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="rad2elev"></a><h3>rad2elev()</h3>
<pre class="programlisting">#define rad2elev(rad)  ((rad)-EARTH_R)
</pre>
<p>
Convert radius to elevation
</p>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>rad</code></em> :</span></p></td>
<td>the radius in meters</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td>the elevation in meters above the earth surface</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="xyz2ll"></a><h3>xyz2ll ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span>                xyz2ll                              (<em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> x</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> y</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> z</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> *lat</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> *lon</code></em>);</pre>
<p>
Get the latitude and longitude for a x, y, z value.
</p>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>x</code></em> :</span></p></td>
<td>the x coordinate</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>y</code></em> :</span></p></td>
<td>the y coordinate</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>z</code></em> :</span></p></td>
<td>the z coordinate</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>lat</code></em> :</span></p></td>
<td>the resulting latitude</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>lon</code></em> :</span></p></td>
<td>the resulting longitude</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="xyz2lle"></a><h3>xyz2lle ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span>                xyz2lle                             (<em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> x</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> y</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> z</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> *lat</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> *lon</code></em>,
                                                         <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> *elev</code></em>);</pre>
<p>
Convert a point from x, y and z coordinates to latitude, longitude, and
elevation.
</p>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>x</code></em> :</span></p></td>
<td>the x coordinate</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>y</code></em> :</span></p></td>
<td>the y coordinate</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>z</code></em> :</span></p></td>
<td>the z coordinate</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>lat</code></em> :</span></p></td>
<td>the resulting latitude</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>lon</code></em> :</span></p></td>
<td>the resulting longitude</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>elev</code></em> :</span></p></td>
<td>the resulting elevation</td>
</tr>
</tbody>
</table></div>
</div>
</div>
</div>
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