Computes the sample standard deviation of a variable's given dimension(s) at all other dimensions.
Available in version 5.1.1 and later.
function dim_stddev_n ( x : numeric, dims [*] : integer ) return_val : float or double
A variable of numeric type and any dimensionality.dims
The dimension(s) of x on which to calculate the standard deviation. Must be consecutive and monotonically increasing.
The output will be double if x is double, and float otherwise.
The output dimensionality will be the same as all but the dims's dimensions of the input variable. The dimension rank of the input variable will be reduced by the rank of dims.
The dim_stddev_n function computes the sample standard deviation of all elements of the dimensions indicated by dims for each index of the remaining dimensions. Missing values are ignored.
Technically, this function calculates the sample standard deviation. This means that it divides by one less than the total number of non-missing values (1/(N-1)).
Use dim_stddev_n_Wrap if retention of metadata is desired.
Create a variable q of size (3,5,10) array. Then calculate the sample standard deviation of the rightmost dimension.
q = random_uniform(-20,100,(/3,5,10/)) qStd= dim_stddev_n(q,2) ;==> qStd(3,5)Example 2
Let x be of size (ntim,nlat,mlon) and with named dimensions "time", "lat" and "lon", respectively. Then, for each time and latitude, the the standard deviation is:
xStdLon= dim_stddev_n( x, 2 ) ; ==> xStdLon(ntim,nlat)Generally, users prefer that the returned variable have metadata associated with it. This can be accomplished via the dim_stddev_n_Wrap function
xStdLon = dim_stddev_n_Wrap( x, 2 ) ; ==> xStdLon(time,lat)Example 3
Let x be defined as in Example 2: x(time,lat,lon). Compute the temporal standard deviation at each latitude/longitude grid point.
xStdTime = dim_stddev_n( x, 0 ) ; ==> xStdTime(nlat,nlon)If metadata is desired use
xStdTime = dim_stddev_n_Wrap( x, 0 ) ; ==> xStdTime(lat,lon)Example 4
Let x be defined as x(time,lev,lat,lon). Compute the temporal standard deviation at each latitude/longitude grid point.
xStd = dim_stddev_n( x, (/0,1/) ) ; ==> xStd(nlat,nlon)Compute the temporal standard deviation at each time/level grid point:
xStd = dim_stddev_n( x, (/2,3/) ) ; ==> xStd(nlev,ntim)