Hello, I have written 3D FDTD code with Mur ABC which gives correct results for time domain data. Now I want to compute the resonance frequency of a rectangular cavity using this 3D FDTD code. I donot know how I will do that. Would someone please advise me the steps I need to follow now to calculate the rectangular cavity resonance frequency. Any code or help on how the time domain data need to be processed is highly appreciated. Thank you.