Distorsion simulation

[bnilsson11]

Hi,

I am trying to simulate the harmonic distorsion of my circuit, starting with the distortion example.
Reading the ngspice manual, I am stuck on the following:
"To obtain HD2 and HD3, one must divide by the corresponding AC values at F1, obtained from an .ac line. This division can be done again using interactive or control commands."
How should the nutmeg equation be formulated to do this?
I am simply getting lost in the syntax...

[tomhajjar]

Here are some examples I have collected.

Dist.zip