How is Fourier wavelength derived?

[robertsawko]

Hi Aaren,

I am trying to compare your code with PyWavelet. My main objective is adding cone of influence visualisation for CWT in PyWavelet. I am using your bias example with three frequencies. I am using expression for COI taken from Table 1 in Torrence and Combo and I am computing my frequencies using scale2frequencies from PyWavelet which uses scaled central frequency and I additionally scale it by sampling period.

The picture I am getting is close to what I expect but not quite. COI is over-predicted which I think is due to the Fourier wavelength calculation or frequency-scale relationship. Could you perhaps tell me how Fourier wavelength is derived?