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# pdfxy_bin

Performs looping necessary to calculate the bivariate (joint) probability distribution (see pdfxy). Available in version 5.1.1 and later.

## Prototype

```	procedure pdfxy_bin (
x           : numeric ,
y           : numeric ,
binxbnd [*] : numeric ,
binybnd [*] : numeric ,
opt      : logical
)
```

## Arguments

x
y

Arrays of any dimensionality. The arrays must be the same size.

binxbnd
binybnd

One dimensional arrays containing the bin boundaries for the x and y arrays, respectively.

opt

If opt=False, then the PDF will be returned in units of percent (%). If opt=True and opt@fraction=True then the units will be 'fraction'.

## Description

This function is designed to be called by pdfxy located in the "contributed.ncl" library. However, it can be called as a stand-alone function.

This function was added increase the efficiency of the multiple looping necessary to calculate the joint probability distribution function (PDF).

## Examples

Example 1

This function was meant to be invoked by pdfxy. However, it can be invoked directly.

```
x     = random_normal( 0,50, (/96,144/))
y     = random_normal (40,25, dimsizes(x))

binx  = fspan(-200,202,21)
biny  = fspan( -50,144,19)

pdf   = pdfxy_bin(x,y, binx,biny, False)
```
If the PDF is to have units of 'fraction', use
```  opt   = True
opt@fraction = True
pdf   = pdfxy_bin(x,y, binx,biny, opt)
```