The "weirdness" to which I was referring here was because rfft~ didin't have a nyquist component of the signal. So, the error was around .001 for regular tones and varied according to slight phase shifts, between 0 and 1 at the Nyquist frequency. So, I switched to fft~ and ifft~ and the error dropped to 10^-8 (which is aprox. 1/24 bits of precision). I am using Pd-extended-38.4. Don't know if this has already been reported or fixed. I'm lagging behind current releases :) Chuck