Get single-sided spectrum from time signal and viceversa

Codes to get single-sided frequency domain signal and time-domain signal from the single-sided frequency-domain signal.

Attached are two simple functions to perform the basic operations in every-day signal processing. The function 'dofft' takes a time-domain signal and Sampling frequency and returns a complex vector of the single-sided spectrum. The function 'doifft' takes the single-sided spectrum (complex) and returns the original time-domain signal. An example is also attached for beginners.