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query_disc
Routine to find the index of all pixels within an angular distance radius from a defined
center. 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_disc(
nside, vector0, radius, listpix, nlist [, nest, inclusive]
)
ARGUMENTS
| name & dimensionality |
kind |
in/out |
description |
|---|
| |
|
|
|
|
nside |
I4B |
IN |
the Nside parameter of the map. |
| vector0(3) |
DP |
IN |
cartesian vector pointing at the disc center. |
| radius |
DP |
IN |
disc radius in radians. |
| listpix(0:*) |
I4B |
OUT |
the index for all pixels within radius. 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 disc are listed, otherwise only those whose
center lies within the disc are listed. |
EXAMPLE:
call query_disc(256,(/0,0,1/),pi/2,listpix,nlist,nest=1)
Returns the NESTED pixel index of all pixels north of the equatorial line in a Nside=256 map.
MODULES & ROUTINESThis section lists the modules and routines used by query_disc.
-
in_ring
- routine to find the pixels in a certain slice of a given ring.
-
ring_num
- function to return the ring number corresponding to the coordinate z
RELATED ROUTINESThis section lists the routines related to query_disc
-
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
Eric Hivon
2010-06-18
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