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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 (scalar integer), should be a valid Nside (power of 2 in $\{1,\ldots,8192\}$)
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

\begin{displaymath}{N_{\rm template}}=\frac{1+{N_{\rm side}}({N_{\rm side}}+6)}{4}.\end{displaymath}

If the argument ${N_{\rm side}}$ 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 6.1 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

Eric Hivon 2010-06-18
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