In its simplest shape, the pseudosinusoidal signal given by an arbitrary wave form generator is constituted by a continuation of samples which involve the presence of parasitic harmonics and an increase in its total harmonic distortion (THD) value. It seems evident that the signal shape can be improved by using a linear interpolation between two consecutive samples but, to our knowledge, this improvement is not evaluated quantitatively to date. So, we propose to calculate this THD (according to the number of samples used to build the signal) with or without linear interpolation. SPICE simulations and experimental results agree with theory.