The χ²pdf( Command

We're glad you came by, but you might find what you're looking for elsewhere. TI-Basic Developer is not the site it once was. While its information on commands and other calculator features remains almost second-to-none, its forum, archives, and even hosting service, Wikidot, have been decaying for years. The calculator community would love to see what you're working on, or help you in your next coding adventure, but TI-Basic Developer is no longer the place to do it. Instead, you should head over to Cemetech (primarily American) or TI-Planet (primarily international). Both are active, well-established forums with their own archives, chatrooms, reference material, and abundant coding tools and resources. We'll see you there, we hope.

Command Summary

Evaluates the χ² probability density function at a point.

Command Syntax

χ²pdf(x, df

Menu Location

Press:

1. 2ND DISTR to access the distribution menu
2. 6 to select χ²pdf(, or use arrows.

Press 7 instead of 6 on a TI-84+/SE with OS 2.30 or higher.

Calculator Compatibility

TI-83/84/+/SE

Token Size

2 bytes

χ²pdf( is the χ² probability density function.

Since the χ² distribution is continuous, the value of χ²pdf( doesn't represent an actual probability — in fact, one of the only uses for this command is to draw a graph of the χ² curve. You could also use it for various calculus purposes, such as finding inflection points.

The command takes two arguments: the value at which to evaluate the p.d.f., and df, the number of 'degrees of freedom'.

Formulas

The value of χ²pdf( is given by

(1)

\begin{align} \operatorname{\chi^2pdf}(x,k)=\frac{(1/2)^{k/2}}{(k/2-1)!}\,x^{k/2-1}e^{-x/2} \end{align}

Related Commands

• χ²cdf(
• Shadeχ²(

.