nside2ntemplates

This IDL facility provides the number of template pixels Ntemplates corresponding to resolution parameter Nside. Each template pixel has a different shape that can not be matched (by rotation or reflexion) to that of any of the other templates.

Location in HEALPix directory tree: src/idl/toolkit/nside2ntemplates.pro 

FORMAT

IDL> Ntemplates=NSIDE2NTEMPLATES (Nside[,ERROR=])

QUALIFIERS

Nside

HEALPix resolution parameter (integer, scalar or not), should be a valid Nside (power of 2 in $\{1,\ldots,2^{29}\}$)

Ntemplates

number of templates

KEYWORDS

ERROR=

error flag, set to 1 on output if Nside is NOT valid, or stays to 0 otherwise.

DESCRIPTION

nside2ntemplates outputs the number of template pixels

$$N_{\mathrm{template}}=\frac{1+N_{\mathrm{side}}(N_{\mathrm{side}}+6)}{4}.$$

If the argument N_side is not valid, a warning is issued and the error flag is raised.

RELATED ROUTINES

This section lists the routines related to nside2ntemplates

idl

version 6.4 or more is necessary to run nside2ntemplates .

template_pixel_ring

template_pixel_nest

return the template pixel associated with any HEALPix pixel

same_shape_pixels_ring

same_shape_pixels_nest

return the ordered list of pixels having the same shape as a given pixel template

EXAMPLE:

Ntemplates = nside2ntemplates(256, ERROR=error)

Ntemplates will be 16768 the number of template pixels for the HEALPix resolution parameter 256 and error will be 0