using gnuplot's thru-command in Octave?

[mats . jansson]

Hi!

In gnuplot one can use the command "thru".
e.g.

gnuplot> f(x)=20*log10(x)
gnuplot> plot "datafile" thru f(x) using 1:2

This results in a plot with the data from column number one in "datafile"
on the abscissa, and the data from column number two passing thru the
function f(x) on the ordinata.

How does one do the same thing (if possible) in Octave? (Without first
reading the file, converting the text into floating numbers and then
calculating the new values.)

Thanks!

/Mats