# Planck and Rosseland Means¶

With the `doMean`

option in the `param.dat`

file, the Plank and Rosseland means,
\(\kappa_P\) and \(\kappa_R\) respectively:

and

can be calculated, where the infinity integral is truncated to the specified wavenumber limits, and \(d\nu\) is
equal to `dnu`

set in the `param.dat`

file.

Note that the denominators in \(\kappa_P\) and \(\kappa_R\) can be computed analytically as

and

Therefor, it is usefull to compare those analytic results to the numerical integration

and

The results of the Planck and Resseland means are stored in the file `Out<name>_mean.dat`

, together with
the analytic and numerical expressions (10) to (13). If the numerical expressions deviate strongly
from the analytical expression, then it is a hint that the wavenumber resolution is not set fine enough.

An example of the Planck and Rosseland means is shown in Fig. 12.

doStoreFullK = 1

doMean = 1