The root mean square (abbreviated RMS or rms), also known as the quadratic mean in statistics is a statistical measure defined as the square root of the mean of the squares of a sample. In physics it is a value characteristic of a continuously varying quantity, such as a cyclically alternating electric current, obtained by taking the mean of the squares of the instantaneous values during a cycle. This is the effective value in the sense of the value of the direct current that would produce the same power dissipation in a resistive load. An electric current of given magnitude produces the same heating regardless of the direction of current flow; squaring the quantity measured ensures that alternation of sign does not invalidate the result. It can be calculated for a sequence of discrete values, or for a continuously varying function. The name is simply a description: the square root of the arithmetic mean of the squares of the samples. It is a particular case of the generalized mean, with exponent 2.

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