Compute the cross-power spectral density of two complex functions for a single spherical harmonic degree.

## Usage

cpsd = SHCrossPowerDensityLC (cilm1, cilm2, l)

## Parameters

cpsd : output, complex*16
The cross-power spectral density of the two complex functions for spherical harmonic degree l.
cilm1 : input, complex*16, dimension (2, lmaxin1+1, lmaxin1+1)
The first complex function expressed in complex spherical harmonics.
cilm2 : input, complex*16, dimension (2, lmaxin2+1, lmaxin2+1)
The second complex function expressed in complex spherical harmonics.
l : input, integer
The spherical harmonic degree. This must be less than or equal to the minimum of lmaxin1 and lmaxin2.

## Description

SHCrossPowerDensityLC will calculate the cross-power spectral density of two complex functions expressed in complex 4-pi normalized spherical harmonics for a single spherical harmonic degree l. This is calculated as:

cpsd = Sum_{i=1}^2 Sum_{m=0}^l cilm1(i, l+1, m+1) * conjg[cilm2(i, l+1, m+1)] / (2l + 1).