npix2nside

Function to provide the resolution parameter $N_{\mathrm{side}}$ correspoonding to $N_{\mathrm{pix}}$ pixels over the full sky.

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

FORMAT

var=npix2nside( npix )

ARGUMENTS

name & dimensionality	kind	in/out	description
npix	I4B/ I8B	IN	the number $N_{\mathrm{pix}}$ of pixels over the whole sky.
var	I4B	OUT	the parameter $N_{\mathrm{side}}$. If $N_{\mathrm{pix}}$ is valid (12 times a power of 2 in $\{1,\ldots,2^{28}\}$), $N_{\mathrm{side}}=\sqrt{N_{\mathrm{pix}}/12}$ is returned; if not, an error message is issued and -1 is returned.

EXAMPLE:

use healpix_modules
integer(I4B) :: nside
nside= npix2nside(786432)

Returns the resolution parameter $N_{\mathrm{side}}$ (256) corresponding to 786432 pixels on the sky.

RELATED ROUTINES

This section lists the routines related to npix2nside

nside2npix

returns the number of pixels $N_{\mathrm{pix}}$ correspondinng to resolution parameter $N_{\mathrm{side}}$