This subroutine returns the number and locations (in terms of pixel
numbers) of the topological neighbours of a central pixel. The pixels
are ordered in a clockwise sense about the central pixel with the
southernmost pixel in first element. For the 4 pixels in the southern corners of the
equatorial faces which have two equally southern neighbours the
routine returns the southwestern pixel first and proceeds clockwise.
This returns nneigh=8 and a vector list, which contains the pixel
numbers ( 90, 0, 2, 3, 6, 4, 94, 91).
MODULES & ROUTINES
This section lists the modules and routines used by neighbours_nest.
mk_xy2pix, mk_pix2xy
precomputing arrays for the conversion
of NESTED pixel numbers to Cartesian coords in each face.
pix2xy_nest, xy2pix_nest
Conversion between NESTED pixel numbers to Cartesian coords in each face.
bit_manipulation
module, containing:
invMSB, invLSB,swapLSBMSB,invswapLSBMSB
functions which manipulate the bit vector which
represents the NESTED pixel numbers. They correspond to
NorthWest<->SouthEast, SouthWest<->NorthEast, East<->West and
North-South flips of the diamond faces, respectively.
RELATED ROUTINES
This section lists the routines related to neighbours_nest