There is this piece from Alvin Lucier "In Memoriam Jon Higgings" for A-Clarinet and sine wave oscillator. The wave oscillator is doing a very slow even glissando starting from a low C (130.81279 Hz)and is arriving after 19'30'' at an (3 Octaves and a third) higher Eb (1244.507935 Hz). To get an equal dispensation of the semitones (every 30 seconds another semitone (as it is written in the score))I need a formula which take the expotential(?)ascending of the frequencies in account (like A=440Hz, A'=880, A''=1760Hz).
Do I need to build an expotential function or the opposite (logarithm(?))?
and would I do that?
Any coaching is much apprechiated