sphere_distance()

double sphere_distance	(	const GEOGRAPHIC_POINT *	s,
		const GEOGRAPHIC_POINT *	e
	)

Given two points on a unit sphere, calculate their distance apart in radians.

Definition at line 948 of file lwgeodetic.c.

{
        double d_lon, cos_d_lon, cos_lat_e, sin_lat_e, cos_lat_s, sin_lat_s;
        double a1, a2, a, b;
 
        if (FP_EQUALS(s->lat, e->lat) && FP_EQUALS(s->lon, e->lon)) return 0.0;
        d_lon = e->lon - s->lon;
        cos_d_lon = cos(d_lon);
        cos_lat_e = cos(e->lat);
        sin_lat_e = sin(e->lat);
        cos_lat_s = cos(s->lat);
        sin_lat_s = sin(s->lat);
 
        a1 = POW2(cos_lat_e * sin(d_lon));
        a2 = POW2(cos_lat_s * sin_lat_e - sin_lat_s * cos_lat_e * cos_d_lon);
        a = sqrt(a1 + a2);
        b = sin_lat_s * sin_lat_e + cos_lat_s * cos_lat_e * cos_d_lon;
        return atan2(a, b);
}

References FP_EQUALS, GEOGRAPHIC_POINT::lat, GEOGRAPHIC_POINT::lon, POW2, and s.

Referenced by circ_internal_nodes_sort(), circ_node_internal_new(), circ_node_leaf_new(), circ_node_max_distance(), circ_node_min_distance(), circ_tree_distance_tree(), circ_tree_distance_tree_internal(), edge_calculate_gbox_slow(), edge_distance_to_point(), geography_interpolate_points(), geography_substring(), interpolate_point4d_spheroid(), ptarray_distance_spheroid(), ptarray_length_spheroid(), ptarray_locate_point_spheroid(), ptarray_segmentize_sphere(), test_sphere_direction(), and test_sphere_project().

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