#include <math.h>
#include "pi.h"
#include <grass/gis.h>
Go to the source code of this file.
Functions | |
int | G_begin_zone_area_on_ellipsoid (double a, double e2, double s) |
begin area calculations for ellipsoid | |
double | G_darea0_on_ellipsoid (register double lat) |
double | G_area_for_zone_on_ellipsoid (register double north, register double south) |
area between latitudes |
double G_area_for_zone_on_ellipsoid | ( | register double | north, | |
register double | south | |||
) |
area between latitudes
Returns the area between latitudes north and south scaled by the factor s passed to G_begin_zone_area_on_ellipsoid.
north | ||
south |
Definition at line 70 of file area_ellipse.c.
References G_darea0_on_ellipsoid().
int G_begin_zone_area_on_ellipsoid | ( | double | a, | |
double | e2, | |||
double | s | |||
) |
begin area calculations for ellipsoid
Initializes raster area calculations for an ellipsoid, where a is the semi-major axis of the ellipse (in meters), e2 is the ellipsoid eccentricity squared, and s is a scale factor to allow for calculations of part of the zone (s=1.0 is full zone, s=0.5 is half the zone, and s=360/ew_res is for a single grid cell). Note. e2 must be positive. A negative value makes no sense, and zero implies a sphere.
a | ||
e2 | ||
s |
Definition at line 31 of file area_ellipse.c.
Referenced by G_begin_cell_area_calculations().
double G_darea0_on_ellipsoid | ( | register double | lat | ) |
Definition at line 43 of file area_ellipse.c.
References Radians, and sin().
Referenced by G_area_for_zone_on_ellipsoid(), and G_begin_cell_area_calculations().