1. The problem statement, all variables and given/known data Lets say I have a square wave of 10Hz. I want a good sampling frequency or the Nyquist rate (minimum) to accurately capture its characteristics without aliasing. Is it enough to use 10Hz x 2 as nyquist rate, or must I break it down into harmonic frequencies? and use maximum harmonic frequency as the sampling rate? What if I do not use the square wave function, but instead sum together harmonic frequencies? Do i still use Fmax as 10 Hz, or use the highest harmonic frequency as Fmax? 2. Relevant equations sin 2πft + 1/3 sin 2π3ft + 1/5 sin 2π5ft +1/7 sin 2π7ft ... am asking that if i use eg. 4 harmonics, must I use Fmax = 70Hz ? or if i sum together 20 harmonics and use Fmax = 10Hz can i still preserve the signal. (not necessarily using 2 x Fmax - nicer shape plot may use 10 x Fmax.) 3. The attempt at a solution something to do with too few sampling points not being able to reproduce shape of square waves and instead getting it wrong. But not sure whether this affects the frequency information extracted during plotting. not sure how summing together harmonics affects result.