# Ngl.chiinv

Evaluates the inverse chi-squared distribution function.

*Available in version 1.3.0 or later.*

## Prototype

x = Ngl.chiinv(p,df)

## Arguments

*p*

A multi-dimensional array or scalar value equal to the integral of the
chi-square distribution. [0<*p*<1]

*df*

A multi-dimensional array of the same size as *p* equal to the
degrees of freedom of the chi-square distribution. (0, +infinity)

## Return value

*x*

A multi-dimensional array of the same size as *p*.

## Description

This function evaluates the inverse chi-squared distribution function by calculating the upper integration of the non-central chi-square distribution. This gives the same answers as IMSL's "chiin" function.

## Examples

The following:

import Ngl p = 0.99 df = 2. x =produces:Ngl.chiinv(p,df) print "p =",p,"df =",df,"x=",x df = 64. x =Ngl.chiinv(p,df)

p = 0.99 df = 2.0 x= [ 9.21034037] p = 0.99 df = 64.0 x= [ 93.21685966]