nag_rand_discrete_uniform (g05tlc) (PDF version)
g05 Chapter Contents
g05 Chapter Introduction
NAG C Library Manual

NAG Library Function Document

nag_rand_discrete_uniform (g05tlc)

+ Contents

    1  Purpose
    7  Accuracy

1  Purpose

nag_rand_discrete_uniform (g05tlc) generates a vector of pseudorandom integers uniformly distributed over the interval a,b.

2  Specification

#include <nag.h>
#include <nagg05.h>
void  nag_rand_discrete_uniform (Integer n, Integer a, Integer b, Integer state[], Integer x[], NagError *fail)

3  Description

nag_rand_discrete_uniform (g05tlc) generates the next n values yi from a uniform 0,1 generator (see nag_rand_basic (g05sac) for details) and applies the transformation
xi = a+ b-a+1 yi ,
where z is the integer part of the real value z. The function ensures that the values xi lie in the closed interval a,b.
One of the initialization functions nag_rand_init_repeatable (g05kfc) (for a repeatable sequence if computed sequentially) or nag_rand_init_nonrepeatable (g05kgc) (for a non-repeatable sequence) must be called prior to the first call to nag_rand_discrete_uniform (g05tlc).

4  References

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

5  Arguments

1:     nIntegerInput
On entry: n, the number of pseudorandom numbers to be generated.
Constraint: n0.
2:     aIntegerInput
3:     bIntegerInput
On entry: the end points a and b of the uniform distribution.
Constraint: ab.
4:     state[dim]IntegerCommunication Array
Note: the actual argument supplied must be the array state supplied to the initialization functions nag_rand_init_repeatable (g05kfc) or nag_rand_init_nonrepeatable (g05kgc).
On entry: contains information on the selected base generator and its current state.
On exit: contains updated information on the state of the generator.
5:     x[n]IntegerOutput
On exit: the n pseudorandom numbers from the specified uniform distribution.
6:     failNagError *Input/Output
The NAG error argument (see Section 3.6 in the Essential Introduction).

6  Error Indicators and Warnings

NE_BAD_PARAM
On entry, argument value had an illegal value.
NE_INT
On entry, n=value.
Constraint: n0.
NE_INT_2
On entry, a=value and b=value.
Constraint: ba.
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_INVALID_STATE
On entry, state vector has been corrupted or not initialized.

7  Accuracy

Not applicable.

8  Further Comments

None.

9  Example

This example prints five pseudorandom integers from a discrete uniform distribution between -5 and 5, generated by a single call to nag_rand_discrete_uniform (g05tlc), after initialization by nag_rand_init_repeatable (g05kfc).

9.1  Program Text

Program Text (g05tlce.c)

9.2  Program Data

None.

9.3  Program Results

Program Results (g05tlce.r)


nag_rand_discrete_uniform (g05tlc) (PDF version)
g05 Chapter Contents
g05 Chapter Introduction
NAG C Library Manual

© The Numerical Algorithms Group Ltd, Oxford, UK. 2012