[Gretl-users] Scaled Frequency in Periodogram

[Thomas La Bone]

Greetings,

I am playing with sunspot data on a Sunday night, making periodograms in 
various software packages (R, SAS, ITSM, and Gretl). The Gretl 
periodogram is quite nice, with the period on the upper x axis and the 
"scaled frequency" on the lower x axis. None of the other packages 
present scaled frequency as a default (I don't know if they offer it at 
all), and I have been unable to nail down exactly what it is. Can anyone 
  offer a simple explanation of scaled frequency as it is used in Gretl, 
or even better, a specific reference? Thanks.

Tom