I'm afraid there is something wrong. If Ttransform = 2 then "3 Sines" transforms and inverses fine but "3 Cosines" does not retrurn the correct time series after the IFFT. I don't know where the problem lies. I thought that it worked fine on your previous version but unfortunately I can't check it as the latest version overwrote that previous version in my project folder and I can't download it again as you have removed it. Please can you have a look if you still have a previous version available?