GIS Library - Sphereical area calculation routines. More...

#include <math.h>
#include <grass/gis.h>
#include "pi.h"

Include dependency graph for area_sphere.c:

Functions
void	G_begin_zone_area_on_sphere (double r, double s)
	Initialize calculations for sphere. More...

double	G_darea0_on_sphere (double lat)
	Calculates integral for area between two latitudes. More...

double	G_area_for_zone_on_sphere (double north, double south)
	Calculates area between latitudes. More...

Detailed Description

GIS Library - Sphereical area calculation routines.

This program is free software under the GNU General Public License (>=v2). Read the file COPYING that comes with GRASS for details.

Author: Original author CERL

Definition in file area_sphere.c.

Function Documentation

◆ G_area_for_zone_on_sphere()

double G_area_for_zone_on_sphere	(	double	north,
		double	south
	)

Calculates area between latitudes.

This routine shows how to calculate area between two lats, but isn't efficient for row by row since G_darea0_on_sphere() will be called twice for the same lat, once as a south then again as a north.

Returns the area between latitudes north and south scaled by the factor s passed to G_begin_zone_area_on_sphere().

Parameters

	north
[in]	south

Returns: double

Definition at line 70 of file area_sphere.c.

References G_darea0_on_sphere().

◆ G_begin_zone_area_on_sphere()

void G_begin_zone_area_on_sphere	(	double	r,
		double	s
	)

Initialize calculations for sphere.

Initializes raster area calculations for a sphere. The radius of the sphere is r and s is a scale factor to allow for calculations of a part of the zone (see G_begin_zone_area_on_ellipsoid()).

Parameters

r	radius of sphere
s	scale factor

Definition at line 36 of file area_sphere.c.

◆ G_darea0_on_sphere()

double G_darea0_on_sphere ( double lat )

Calculates integral for area between two latitudes.

Parameters

lat latitude

Returns: area value

Definition at line 48 of file area_sphere.c.

References Radians.

Referenced by G_area_for_zone_on_sphere().

Functions

Detailed Description

Function Documentation

◆ G_area_for_zone_on_sphere()

◆ G_begin_zone_area_on_sphere()

◆ G_darea0_on_sphere()