uniq2nest

This F90 facility turns the Unique Identifier $u = p + 4 N_{\mathrm{side}}^2$, into the parameter $N_{\mathrm{side}}$ (a power of 2) and the pixel index $p$. See ”The Unique Identifier scheme” section in ”HEALPix Introduction Document” for more details.

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

FORMAT

call uniq2nest( puniq, nside, pnest )

ARGUMENTS

name	kind	in/out	description
puniq	I4B/I8B	IN	The HEALPix Unique pixel identifier. Must be $\ge 4$.
nside	I4B	OUT	The HEALPix $N_{\mathrm{side}}$ parameter.
pnest	I4B/I8B	OUT	(NESTED scheme) pixel identification number over the range {0, $12N_{\mathrm{side}}^2-1$}.

EXAMPLE:

use healpix_modules
integer(I4B) :: nside, pnest
call uniq2nest(4, nside, pnest)
print*,nside,pnest

returns
1 0
since the pixel with Unique ID number 4 is the first pixel ($p=0$) at $N_{\mathrm{side}}=$ 1.

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