function smd = circularMeanDeviation(x)
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%< circularMeanDeviation >
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%  Returns 'sample circular mean deviation' smd (sample mean deviation).
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%  x = [pi/6, pi/3, pi/2];  % data set
%  tol = 0.0000001;
%  smd = circularMeanDeviation(x,tol);
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%  Unit is radian.
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smd = circularDiff(x, circularMedian(x));