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dim_rmsd

Computes the root-mean-square-difference between two variables' rightmost dimension at all other dimensions.

Prototype

	function dim_rmsd (
		x  : numeric,  
		y  : numeric   
	)

	return_val  :  float or double

Arguments

A variable of numeric type and any dimensionality.

A variable of numeric type and same dimensionality as x.

Return value

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

The output dimensionality is the same as the first n-1 dimensions of the input variable. That is, the dimension rank of the input variable will be reduced by one.

Description

The dim_rmsd function computes the root-mean-square-difference of all elements of the n-1 dimension for each index of the dimensions 0...n-2. Missing values are ignored.

Use dim_rmsd_n if you want to specify which dimension(s) to do the calculation on.

Use dim_rmsd_Wrap if retention of metadata is desired.

Examples

Example 1

Create two variables q nd r of size (3,5,10) array. Then calculate the root-mean-square-difference of the rightmost dimension.

    q   = random_uniform(-20,100,(/3,5,10/))
    r   = random_uniform(-50, 99,(/3,5,10/))
    rmsd= dim_rmsd(q,r)   ;==>  rmsd(3,5)

Example 2

Let x and y be of size (ntim,nlat,mlon) and with named dimensions "time", "lat" and "lon", respectively. Then, for each time and latitude, the root-mean-square-difference is:

    rmsdLon= dim_rmsd( x,y )    ; ==> rmsdLon(ntim,nlat)

Generally, users prefer that the returned variable have metadata associated with it. This can be accomplished via the dim_rmsd_Wrap function:

    rmsdLon = dim_rmsd_Wrap( x,y )    ; ==> rmsdLon(time,lat)

Example 3

Let x be defined as in Example 2: x(time,lat,lon). Compute the temporal root-mean-square-difference at each latitude/longitude grid point. Use NCL's Named Subscripting to reorder the input array such that "time" is the rightmost dimension. Note: in V5.1.1, you will be able to use dim_rmsd_n to avoid having to reorder your data.

    rmsdTime = dim_rmsd( x(lat|:,lon|:,time|:), y(lat|:,lon|:,time|:) )    ; ==> rmsdTime(nlat,nlon)

    rmsdTime = dim_rmsd_n( x, y, 0 )                                       ; ==> no reordering needed

If metadata is desired use