## `stats::ChiSquare` -- the ``Chi Square'' distribution

#### Introduction

`stats::ChiSquare``(x, v)` computes the value

    1/gamma(v/2)/2^(v/2) * int(t^(v/2-1)*exp(-t/2), t = 0..x)

of the Chi Square distribution with v degrees of freedom at the point x.

#### Call(s)

`stats::ChiSquare(x, v)`

#### Parameters

`x` | - | an arithmetical expression.
`v` | - | the ``degrees of freedom'': a positive integer.

#### Returns

an arithmetical expression.

#### Side Effects

The function is sensitive to the environment variable `DIGITS`, when the argument `x` is a floating point number.

#### Related Functions

`stats::normal`, `stats::Tdist`

#### Details

- The integral is evaluated by an explicit formula.

#### Example 1

We compute the Chi Square distribution with one degree of freedom at the point x=2.4:

    >> stats::ChiSquare(2.4, 1)

                                   0.8786647497

#### Example 2

We compute the Chi Square distribution with four degrees of freedom at a symbolic point:

    >> stats::ChiSquare(x, 4)

                                              /   x \
                                 (2 x + 4) exp| - - |
                                              \   2 /
                             1 - --------------------
                                          4

#### Changes

- no changes

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