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query_triangle
Routine to find the index of all pixels enclosed in a spherical triangle described by its three vertices. The output indices can be either in the RING or NESTED scheme
Location in HEALPix directory tree:
src/f90/mod/pix_tools.f90
FORMAT call query_triangle(
nside, v1, v2, v3, listpix, nlist [, nest, inclusive]
)
ARGUMENTS
| name&dimensionality |
kind |
in/out |
description |
|---|
| |
|
|
|
|
nside |
I4B |
IN |
the Nside parameter of the map. |
| 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. |
| listpix(0:*) |
I4B |
OUT |
the index for all pixels enclosed in the triangle. Make sure that the size of the array is big enough to contain all pixels. |
| nlist |
I4B |
OUT |
The number of pixels listed in listpix. |
| nest (OPTIONAL) |
I4B |
IN |
The pixel indices are in the NESTED numbering scheme if nest=1, and in RING scheme otherwise. |
| inclusive (OPTIONAL) |
I4B |
IN |
If set to 1, all the pixels overlapping
(even partially)
with the triangle are listed, otherwise only those whose
center lies within the triangle are listed. |
EXAMPLE:
call query_triangle(256,(/1,0,0/),(/0,1,0/),(/0,0,1/),listpix,nlist)
Returns the RING pixel index of the (98560) pixels in the octant (x,y,z>0) in a Nside=256 map.
MODULES & ROUTINESThis section lists the modules and routines used by query_triangle.
-
in_ring
- routine to find the pixels in a certain slice of a given ring.
-
intrs_intrv
- routine to compute the intersection of 2 intervals on a circle
-
ring_num
- function to return the ring number corresponding to the coordinate z
-
vect_prod
- routine to compute the vectorial product of two 3D vectors
RELATED ROUTINESThis section lists the routines related to query_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
-
surface_triangle
- computes the surface of a spherical triangle defined by 3 vertices
Eric Hivon
2010-06-18
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