[sdiy] math question - somewhat OT

[jbv]

Hi folks,

I have a blank.
I want to represent frequencies (partials of a sound
for instance) on a linear scale (instead of exponential).
IOW the distance between the following values :
220, 440, 880, 1760 should be equal (but the freqs
aren't always perfect harmonics values).
How do I compute that ?

Thanks,
JB