# NAG CL Interfaceg08cjc (gofstat_​anddar_​unif)

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## 1Purpose

g08cjc calculates the Anderson–Darling goodness-of-fit test statistic and its probability for the case of standard uniformly distributed data.

## 2Specification

 #include
 void g08cjc (Integer n, Nag_Boolean issort, double y[], double *a2, double *p, NagError *fail)
The function may be called by the names: g08cjc, nag_nonpar_gofstat_anddar_unif or nag_anderson_darling_uniform_prob.

## 3Description

Calculates the Anderson–Darling test statistic ${A}^{2}$ (see g08chc) and its upper tail probability by using the approximation method of Marsaglia and Marsaglia (2004) for the case of uniformly distributed data.
Anderson T W and Darling D A (1952) Asymptotic theory of certain ‘goodness-of-fit’ criteria based on stochastic processes Annals of Mathematical Statistics 23 193–212
Marsaglia G and Marsaglia J (2004) Evaluating the Anderson–Darling distribution J. Statist. Software 9(2)

## 5Arguments

1: $\mathbf{n}$Integer Input
On entry: $n$, the number of observations.
Constraint: ${\mathbf{n}}>1$.
2: $\mathbf{issort}$Nag_Boolean Input
On entry: set ${\mathbf{issort}}=\mathrm{Nag_TRUE}$ if the observations are sorted in ascending order; otherwise the function will sort the observations.
3: $\mathbf{y}\left[{\mathbf{n}}\right]$double Input/Output
On entry: ${y}_{\mathit{i}}$, for $\mathit{i}=1,2,\dots ,n$, the $n$ observations.
On exit: if ${\mathbf{issort}}=\mathrm{Nag_FALSE}$, the data sorted in ascending order; otherwise the array is unchanged.
Constraint: if ${\mathbf{issort}}=\mathrm{Nag_TRUE}$, the values must be sorted in ascending order. Each ${y}_{i}$ must lie in the interval $\left(0,1\right)$.
4: $\mathbf{a2}$double * Output
On exit: ${A}^{2}$, the Anderson–Darling test statistic.
5: $\mathbf{p}$double * Output
On exit: $p$, the upper tail probability for ${A}^{2}$.
6: $\mathbf{fail}$NagError * Input/Output
The NAG error argument (see Section 7 in the Introduction to the NAG Library CL Interface).

## 6Error Indicators and Warnings

NE_ALLOC_FAIL
Dynamic memory allocation failed.
See Section 3.1.2 in the Introduction to the NAG Library CL Interface for further information.
On entry, argument $⟨\mathit{\text{value}}⟩$ had an illegal value.
NE_BOUND
The data in y must lie in the interval $\left(0,1\right)$.
NE_INT
On entry, ${\mathbf{n}}=⟨\mathit{\text{value}}⟩$.
Constraint: ${\mathbf{n}}>1$.
NE_INTERNAL_ERROR
An internal error has occurred in this function. Check the function call and any array sizes. If the call is correct then please contact NAG for assistance.
See Section 7.5 in the Introduction to the NAG Library CL Interface for further information.
NE_NO_LICENCE
Your licence key may have expired or may not have been installed correctly.
See Section 8 in the Introduction to the NAG Library CL Interface for further information.
NE_NOT_INCREASING
${\mathbf{issort}}=\mathrm{Nag_TRUE}$ and the data in y is not sorted in ascending order.

## 7Accuracy

Probabilities greater than approximately $0.09$ are accurate to five decimal places; lower value probabilities are accurate to six decimal places.

## 8Parallelism and Performance

g08cjc is threaded by NAG for parallel execution in multithreaded implementations of the NAG Library.
Please consult the X06 Chapter Introduction for information on how to control and interrogate the OpenMP environment used within this function. Please also consult the Users' Note for your implementation for any additional implementation-specific information.

None.

## 10Example

This example calculates the ${A}^{2}$ statistic and its $p$-value for uniform data obtained by transforming exponential variates.

### 10.1Program Text

Program Text (g08cjce.c)

### 10.2Program Data

Program Data (g08cjce.d)

### 10.3Program Results

Program Results (g08cjce.r)