Give the number of pixel for the given nside.
Parameters : | nside : int
|
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Returns : | npix : int
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Notes
Raise a ValueError exception if nside is not valid.
Examples
>>> import healpy as hp
>>> hp.nside2npix(8)
768
>>> np.all([hp.nside2npix(nside) == 12 * nside**2 for nside in [2**n for n in range(12)]])
True
>>> hp.nside2npix(7)
Traceback (most recent call last):
...
ValueError: Given number is not a valid nside parameter (must be a power of 2)