transformcl.cltovar

transformcl.cltovar(cl)

compute variance from angular power spectrum

Given the angular power spectrum, compute the variance of the spherical random field in a point.

Parameters:

clarray_like

Angular power spectrum. Can be multidimensional, with the last axis representing the modes.

Returns:

var: float

The variance of the given power spectrum.

Notes

The variance \(\sigma^2\) of the field with power spectrum \(C_l\) is

\[\sigma^2 = \sum_{l} \frac{2l + 1}{4\pi} \, C_l \;.\]