Chi2cdf

Description

Computes the lower/upper tail probability for the \(\chi^2\) distribution with real degrees of freedom df.

Syntax

double prob = chi2cdf(double x, double df[, int tail])

Parameters

x

Input, the value of the Chi variate, must be nonnegative (\(x>=0\)).

df

Input, the degrees of freedom, \(\nu\), of the distribution, \(\chi^2\) must be positive(\(df>0\)).

tail

Input, Optional. The tail probability type using for the \(\chi^2\) distribution

• 1 = the for upper tail probability
• 2 = the lower tail probability (Default if not set)

prob

Output, the returned probability.

Example

chi2cdf(150,3,1)=;     // ANS: 2.6349139284881E-32