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dim_stddev_n

Computes the sample standard deviation of a variable's given dimension(s) at all other dimensions.

Prototype

	function dim_stddev_n (
		x        : numeric,  
		dims [*] : integer   
	)

	return_val  :  float or double

Arguments

x

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.

Return value

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.

Description

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 the dim_stddev_n_Wrap function if metadata retention is desired. The interface is identical.

See Also

dim_stddev_n_Wrap, dim_stddev_Wrap, stddev, dim_avg, dim_median, dim_num, dim_product, dim_rmsd, dim_rmvmean, dim_rmvmed, dim_standardize, dim_stat4, dim_stddev, dim_sum, dim_variance

Examples

Example 1

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)

    ; Use dim_stddev_n_Wrap if metadata retention is desired
    ; qStd= dim_stddev_n_Wrap(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)

    ; Use dim_stddev_n_Wrap if metadata retention is desired
    ; 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)

    ; Use dim_stddev_n_Wrap if metadata retention is desired
    ; 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)

    ; Use dim_stddev_n_Wrap if metadata retention is desired
    ; 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)

    ; Use dim_stddev_n_Wrap if metadata retention is desired
    ; xStd = dim_stddev_n_Wrap( x, (/2,3/) ) ; ==> xStd(nlev,ntim)

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