# 3. UsageΒΆ

The `corfu`

package contains functionality to project three-dimensional
correlation functions and power spectra along lines of sight to obtain the
angular correlation function and angular power spectrum on the sphere. The
general process is as follows.

If you have a 3d power spectrum, such as the matter power spectrum obtained e.g. from CAMB, CLASS, or Eisenstein-Hu, use the

`corfu.ptoxi()`

function to obtain the 3d (matter) correlation function.If the objective is the computation of an angular power spectrum, use the

`corfu.theta()`

function to obtain a set of evaluation points.If you have a 3d (matter) correlation function and filter functions along the line of sight, use the

`corfu.xitow()`

function to obtain the projected angular correlation function.If you have the angular correlation function, use the

`corfu.wtocl()`

function to obtain the angular power spectrum.