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query_strip
Routine to find the index of all pixels enclosed in a latitude strip. 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_strip(
nside, theta1, theta2, listpix, nlist [, nest, inclusive]
)
ARGUMENTS
| name&dimensionality |
kind |
in/out |
description |
|---|
| |
|
|
|
|
nside |
I4B |
IN |
the Nside parameter of the map. |
| theta1 |
DP |
IN |
colatitude lower bound in radians measured from North Pole
(between 0 and  ). |
| theta2 |
DP |
IN |
colatitude upper bound in radians measured from North Pole (between 0 and ). If
theta1< theta2, the pixels lying in [theta1,theta2]
are output, otherwise, the pixel lying in [0,
theta2] and those lying in [theta1, ] are output. |
| listpix(0:*) |
I4B |
OUT |
the index for all pixels enclosed in the
strip(s). 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 strip are listed; otherwise only those whose
center lies within the strip are listed. |
EXAMPLE:
call query_strip(256,0.75*PI,0.2*PI,listpix,nlist,nest=1)
Returns the NESTED pixel index of all pixels with colatitude in
[0, ] and those with colatitude in [ ,]
MODULES & ROUTINESThis section lists the modules and routines used by query_strip.
-
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_strip
-
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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