npix2nside


Function to provide the resolution parameter ${N_{\rm side}}$ correspoonding to ${N_{\rm pix}}$ 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 ${N_{\rm pix}}$ of pixels over the whole sky.
var I4B OUT the parameter ${N_{\rm side}}$. If ${N_{\rm pix}}$ is valid (12 times a power of 2 in $\{1,\ldots,2^{28}\}$), ${N_{\rm side}}=\sqrt{{N_{\rm pix}}/12}$ 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 ${N_{\rm side}}$ (256) corresponding to 786432 pixels on the sky.

RELATED ROUTINES

This section lists the routines related to npix2nside

nside2npix
returns the number of pixels ${N_{\rm pix}}$ correspondinng to resolution parameter ${N_{\rm side}}$

Version 3.31, 2017-01-06