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# dim_stddev

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

## Prototype

```	function dim_stddev (
x  : numeric
)

return_val  :  float or double
```

## Arguments

x

A variable of numeric type and any dimensionality.

## Return value

The output will be double if x is double, and float otherwise.

The output dimensionality is the same as the first n-2 dimensions of the input variable. That is, the dimension rank of the input variable will be reduced by one.

## Description

The dim_stddev function computes the sample standard deviation of all elements of the n-1 dimension for each index of the dimensions 0...n-2. 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 if you want to specify which dimension(s) to calculate the standard deviation on.

Use the dim_stddev_Wrap function if metadata retention is desired. The interface is identical.

## 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(q)   ;==>  qStd(3,5)

; Use dim_stddev_Wrap if metadata retention is desired
; qStd= dim_stddev_Wrap(q)   ;==>  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( x )    ; ==> xStdLon(ntim,nlat)

; Use dim_stddev_Wrap if metadata retention is desired
; xStdLon = dim_stddev_Wrap( x )    ; ==> 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. Use NCL's named subscripting to reorder the input array such that "time" is the rightmost dimension.

```    xStdTime = dim_stddev( x(lat|:, lon|:, time|:) )    ; ==> xStdTime(nlat,nlon)

; Use dim_stddev_Wrap if metadata retention is desired
; xStdTime = dim_stddev_Wrap( \
;                                        x(lat|:, lon|:, time|:) )    ; ==> xStdTime(lat,lon)

xStdTime = dim_stddev_n( x, 0 )                     ; no reordering needed

; Use dim_stddev_n_Wrap if metadata retention is desired
; xStdTime = dim_stddev_n_Wrap( x, 0 ) ; no reordering needed
```