uniq2nest


This IDL facility turns the Unique Identifier into the corresponding $N_{\rm side}$ and (NESTED) pixel index.

Location in HEALPix directory tree: src/idl/toolkit/uniq2nest.pro 


FORMAT

IDL> uniq2nest, Puniq, Nside, Pnest [,/HELP]


QUALIFIERS

Puniq
(IN, scalar or vector Integer) The HEALPix Unique pixel identifier(s). Must be $\ge 4$.
Nside
(OUT, same size as Puniq) The HEALPix $N_{\rm side}$ parameter(s)
Pnest
(OUT, same size as Puniq) (NESTED scheme) pixel identification number(s) over the range {0, $12N_{\rm side}^2-1$}.


KEYWORDS

/HELP
If set, a documentation header is printed out, and the routine exits


DESCRIPTION

uniq2nest turns the Unique ID number $u = p + 4 N_{\rm side}^2$, into the parameter $N_{\rm side}$ (a power of 2) and the pixel index p. See ''The Unique Identifier scheme'' section in ''HEALPix Introduction Document'' for more details.


EXAMPLE:

uniq2nest, [4,16, 64], nside, pnest
print, nside, pnest
returns
1 2 4
0 0 0
since the pixels with Unique ID numbers 4, 16 and 64 are the first pixels (p=0) at $N_{\rm side}=$ 1, 2 and 4 respectively.


RELATED ROUTINES

This section lists the routines related to uniq2nest

nest2uniq
Transforms Nside and Nested pixel number into Unique HEALPix pixel ID number
pix2xxx, ...
to turn NESTED pixel index into sky coordinates and back

Version 3.31, 2017-01-06