g05 Chapter Contents
g05 Chapter Introduction
NAG C Library Manual

# NAG Library Function Documentnag_rngs_logical (g05kec)

## 1  Purpose

nag_rngs_logical (g05kec) returns a pseudorandom logical value – $\mathit{true}$ with probability $p$ and $\mathit{false}$ with probability $\left(1-p\right)$.

## 2  Specification

 #include #include
 Nag_Boolean nag_rngs_logical (double p, Integer igen, Integer iseed[], NagError *fail)

## 3  Description

nag_rngs_logical (g05kec) returns the logical value of the relation
 $y
where $y$ is a pseudorandom number from a uniform distribution over $\left(0,1\right)$, generated by nag_rngs_basic (g05kac) using the values of igen and iseed as input to this function.
One of the initialization functions nag_rngs_init_repeatable (g05kbc) (for a repeatable sequence if computed sequentially) or nag_rngs_init_nonrepeatable (g05kcc) (for a non-repeatable sequence) must be called prior to the first call to nag_rngs_logical (g05kec).

## 4  References

Knuth D E (1981) The Art of Computer Programming (Volume 2) (2nd Edition) Addison–Wesley

## 5  Arguments

1:     pdoubleInput
On entry: must contain the probability of nag_rngs_logical (g05kec) returning Nag_TRUE.
Constraint: $0.0\le {\mathbf{p}}\le 1.0$.
2:     igenIntegerInput
On entry: must contain the identification number for the generator to be used to return a pseudorandom number and should remain unchanged following initialization by a prior call to nag_rngs_init_repeatable (g05kbc) or nag_rngs_init_nonrepeatable (g05kcc).
3:     iseed[$4$]IntegerCommunication Array
On entry: contains values which define the current state of the selected generator.
On exit: contains updated values defining the new state of the selected generator.
4:     failNagError *Input/Output
The NAG error argument (see Section 3.6 in the Essential Introduction).

## 6  Error Indicators and Warnings

On entry, argument $〈\mathit{\text{value}}〉$ had an illegal value.
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.
NE_REAL
On entry, ${\mathbf{p}}<0.0$ or ${\mathbf{p}}>1.0$: ${\mathbf{p}}=〈\mathit{\text{value}}〉$.

Not applicable.

None.

## 9  Example

This example prints the first five pseudorandom logical values generated by nag_rngs_logical (g05kec) after initialization by nag_rngs_init_repeatable (g05kbc), when the probability of a TRUE value is $0.6$.

### 9.1  Program Text

Program Text (g05kece.c)

None.

### 9.3  Program Results

Program Results (g05kece.r)