In mathematics, the root mean square (abbreviated RMS or rms), also known as the quadratic mean, is a statistical
measure of the magnitude of a varying quantity. It is especially useful when variates are positive and negative,
e.g., sinusoids. It can be calculated for a series of discrete values or for a continuously varying function. The
name comes from the fact that it is the square root of the mean of the squares of the values.
RMS (effective) value of any
periodic function with period T.
...for positive or negative half-cycle