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# dim_product_n

Computes the product of a variable's given dimension(s) at all other dimensions. Available in version 5.1.1 and later.

## Prototype

```	function dim_product_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 product. 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 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_product_n function computes the product of all elements of the dimensions indicated by dims for each index of the remaining dimensions. Missing values are ignored.

## Examples

Example 1

Create a variable, q, of size (3,5,10) array. Then calculate the product of the rightmost dimension.

```    q   = random_uniform(-20,100,(/3,5,10/))
qav = dim_product_n(q,2)   ;==>  qav(3,5)
```
Note: when operating across the rightmost dimension, it is simpler to use dim_product.

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 'zonal product' (i.e., product of all non-missing longitudes) is:

```    xProLon = dim_product_n(x, 2)    ; ==> xProLon(ntim,nlat)
```
Example 3

Let x be defined as in Example 2: x(time,lat,lon). Compute the product over time at each latitude/longitude grid point.

```    xProTime = dim_product_n( x, 0 )    ; ==> xProTime(nlat,nlon)
```
Example 4

Let x be x(time,lev,lat,lon). Compute the product over time and level at each latitude/longitude grid point.

```    xProd = dim_product_n( x, (/0,1/) )    ; ==> xProd(nlat,nlon)
```