xy2pix
Find (nest indexed) MEALPix pixel number corresponding to a pixel index on a HEALPix face
Contents
Syntax
ipix = xy2pix(nSide, ix, iy, nFace)
Input Arguments
nside HEALPix resolution parameter (power of 2) ix,iy integer pixel location on face (1 <= ix, iy <= nSide) nFace HEALPix face number (1 <= nFace <= 12)
One or both ix and iy may be scalars. If neither is a scalar both must have the same size.
Return Arguments
ipix NESTED pixel index for given x,y on the face
Description
At lowest resolution HEALPix divides the sphere into 12 faces, each with its own coordinate system. Each face is further subdivided in a regular fashion as the resolution parameter is increased. Given a face number (from 1 to 12), a resolution parameter, and a location on the face XY2PIX identifies the pixel number (in the nested indexing scheme).
Example
nSide = 4; nFace = 3; ix = [1 2; 1 2]; iy = [1 1; 2 2]; nPix = xy2pix(nSide,ix,iy,nFace)
nPix = 49 50 51 52
See also
pix2xy
Copyright 2010-2011 Lee Samuel Finn. Terms of Use.