#include <math.h>
#include <grass/gis.h>
#include "pi.h"
Go to the source code of this file.
Functions | |
int | G_begin_ellipsoid_polygon_area (double a, double e2) |
begin area calculations | |
double | G_ellipsoid_polygon_area (double *lon, double *lat, int n) |
area of lat-long polygon |
int G_begin_ellipsoid_polygon_area | ( | double | a, | |
double | e2 | |||
) |
begin area calculations
This initializes the polygon area calculations for the ellipsoid with semi-major axis a (in meters) and ellipsoid eccentricity squared e2.
a | ||
e2 |
Definition at line 45 of file area_poly1.c.
References PI.
Referenced by G_begin_polygon_area_calculations().
double G_ellipsoid_polygon_area | ( | double * | lon, | |
double * | lat, | |||
int | n | |||
) |
area of lat-long polygon
Returns the area in square meters of the polygon described by the n pairs of lat,long vertices for latitude-longitude grids. Note. This routine assumes grid lines on the connecting the vertices (as opposed to geodesics.)
lon | ||
lat | ||
n |
Definition at line 88 of file area_poly1.c.
Referenced by G_area_of_polygon().