You're talking about the magnitude, which is spread evenly across the frequency range. The real component of the freq domain representation is in fact sinusoida

You're talking about the magnitude, which is spread evenly across the frequency range. The real component of the freq domain representation is in fact sinusoidal. Time-Frequency duality is a well-known phenomenon in signal processing. > Maybe the author was playing with an FFT library that they just didn't understand properly. There's no need for that.