surface_triangle

Returns the surface in steradians of the spherical triangle described by its three vertices

Location in HEALPix directory tree: src/f90/mod/pix_tools.F90 

FORMAT

call surface_triangle( v1, v2, v3, surface )

ARGUMENTS

name&dimensionality	kind	in/out	description
v1(3)	DP	IN	cartesian vector pointing at the triangle first vertex.
v2(3)	DP	IN	cartesian vector pointing at the triangle second vertex.
v3(3)	DP	IN	cartesian vector pointing at the triangle third vertex.
surface	DP	OUT	surface of the triangle in steradians.

EXAMPLE:

use healpix_types
use pix_tools, only : surface_triangle
real(DP) :: surface, one = 1.0_dp
call surface_triangle((/1,0,0/)*one, (/0,1,0/)*one, (/0,0,1/)*one, surface)
print*, surface

Returns the surface in steradians of the triangle defined by the octant ($x,y,z>0$) : 1.5707963267948966

RELATED ROUTINES

This section lists the routines related to surface_triangle

pix2ang, ang2pix

convert between angle and pixel number.

pix2vec, vec2pix

convert between a cartesian vector and pixel number.

query_disc, query_polygon,

query_strip, query_triangle

render the list of pixels enclosed respectively in a given disc, polygon, latitude strip and triangle