二乗平均(実効値) / Root Mean Square

function y = rms(x)
%RMS   Calculate Root Mean Square of a signal
%   y = rms(x) calculates RMS (Root Mean Square) of input signal x.
%
%   2003-01-09 by MARUI Atsushi
%   2004-10-30 now proper rms calculation

if length(x)~=size(x,1)
  x = x';
end

y = sqrt( sum(x .^ 2) / length(x) );