npix2nside
This IDL facility provides the HEALPix resolution parameter Nside corresponding to Npix
pixels over the full sky.
Location in HEALPix directory tree: src/idl/toolkit/npix2nside.pro
FORMAT
QUALIFIERS
-
Npix
- number of pixels over the full sky (scalar integer),
should be a valid Npix
(
with
power of 2 in
)
-
Nside
- on output: resolution parameter if Npix is valid, -1 otherwise
KEYWORDS
-
ERROR=
- error flag, set to 1 on output if Npix is NOT valid, or
stays to 0 otherwise.
DESCRIPTION
npix2nside checks that the given Npix is valid
(
with
a power of 2 in
) and then computes the
corresponding resolution parameter
.
RELATED ROUTINES
This section lists the routines related to npix2nside
-
idl
- version 6.4 or more is necessary to run npix2nside .
-
nside2npix
- computes Npix corresponding to Nside
-
pix2xxx, ang2xxx, vec2xxx, ...
- conversion between vector or angles and pixel index and vice-versa
-
vec2pix, pix2vec
- conversion between vector and pixel index
-
nest2ring, ring2nest
- conversion between NESTED and RING indices
EXAMPLE:
Nside will be 64 because 49152 is a valid pixel number (=12*642 and 64 is a power of 2), and error will be 0
EXAMPLE:
Nside will be -1 and error: 1, because 49151 is not a valid number of HEALPix
pixels over the full sky.
Version 3.30, 2015-10-08