#include <math.h>
#include <grass/gis.h>
#include "pi.h"
Go to the source code of this file.
Functions | |
int | G_begin_geodesic_distance (double a, double e2) |
begin geodesic distance | |
int | G_set_geodesic_distance_lat1 (double lat1) |
set geodesic distance lat1 | |
int | G_set_geodesic_distance_lat2 (double lat2) |
set geodesic distance lat2 | |
double | G_geodesic_distance_lon_to_lon (double lon1, double lon2) |
geodesic distance | |
double | G_geodesic_distance (double lon1, double lat1, double lon2, double lat2) |
geodesic distance |
int G_begin_geodesic_distance | ( | double | a, | |
double | e2 | |||
) |
begin geodesic distance
Initializes the distance calculations for the ellipsoid with semi-major axis a (in meters) and ellipsoid eccentricity squared e2. It is used only for the latitude-longitude projection.
a | ||
e2 |
Definition at line 37 of file geodist.c.
References sqrt().
Referenced by G_begin_distance_calculations().
double G_geodesic_distance | ( | double | lon1, | |
double | lat1, | |||
double | lon2, | |||
double | lat2 | |||
) |
geodesic distance
Calculates the geodesic distance from lon1,lat1 to lon2,lat2 in meters. The calculation of the geodesic distance is fairly costly. These next three routines provide a mechanism for calculating distance with two fixed latitudes and varying longitude separation.
lon1 | ||
lat1 | ||
lon2 | ||
lat2 |
Definition at line 202 of file geodist.c.
References G_geodesic_distance_lon_to_lon(), G_set_geodesic_distance_lat1(), and G_set_geodesic_distance_lat2().
Referenced by G_distance().
double G_geodesic_distance_lon_to_lon | ( | double | lon1, | |
double | lon2 | |||
) |
geodesic distance
Calculates the geodesic distance from lon1,lat1 to lon2,lat2 in meters, where lat1 was the latitude passed to G_set_geodesic_distance_latl and lat2 was the latitude passed to G_set_geodesic_distance_lat2.
lon1 | ||
lon2 |
Definition at line 119 of file geodist.c.
References PI, Radians, sin(), and sqrt().
Referenced by G_geodesic_distance().
int G_set_geodesic_distance_lat1 | ( | double | lat1 | ) |
int G_set_geodesic_distance_lat2 | ( | double | lat2 | ) |