CryoFaBs

This is the documentation for CryoFaBs. The paper describing the details of the algorithm will be on arXiv shortly.

This package is similar in spirit to Healpix.jl and SphericalFourierBesselDecompositions.jl. It performs a harmonic analysis (usually of galaxy surveys) exploiting the isotropy on the sky despite non-isotropic window functions and masks. It does this in both 2D and 3D.

Installation

To install, add the github repo to your julia project, like so:

julia>] add https://github.com/hsgg/CryoFaBs.jl.git

Basic usage

The central objects of this package are of the abstract type CryoFaB, which behaves like a matrix. For example, if δr is the density contrast in configuration space and cfb is a CryoFaB, then the transform into cryospace is performed via

δnlm = cfb \ δr

CryoFaB-objects like AngularCryoFaB (for 2D on the sphere) and AngRadCryoFaB (for 3D) are also used to convert between pixels (or voxels in 3D) and a cell index, e.g.,

pix = coord2cell(cfb, θ, ϕ)

This is similar to the function ang2pix() from Healpix.jl and indeed it is the same in the 2D case. In 3D the same is done by using a different cfb object of type AngRadCryoFaB and additionally passing a radial coordinate.

The CryoFaB-objects also encode everything that is needed for the pixel window.