Calculates the moving standard deviation of a series.
MOVSTD(series, N, rampflag, mode)
series 
 
A series or table.  
N 
 
An integer, the number of points to compute the standard deviation as the series is processed.  
rampflag 
 
Optional. An integer, endpoint averaging flag.
 
mode 
 
Optional. An integer,
the normalization mode. For

A series or table.
W1: {1, 2, 4, 7}
W2: movstd(W1, 3)
returns the series {0, 0.612, 1.528, 2.517, 1.837, 0}
W3: movstd(W1, length(W1))
W3[length(w1)] == stdev(w1) == 2.645751
MOVSTD computes the moving standard deviation. For each section of length N, the sample standard deviation value (mode == 0) is defined as:
where the arithmetic mean is defined as:
The population standard deviation