nag_rand_discrete_uniform (g05tlc) (PDF version)
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NAG 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 dimension, dim, of this array is dictated by the requirements of associated functions that must have been previously called. This array MUST be the same array passed as argument state in the previous call to 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

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

7  Accuracy

Not applicable.

8  Parallelism and Performance

Not applicable.

9  Further Comments


10  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).

10.1  Program Text

Program Text (g05tlce.c)

10.2  Program Data


10.3  Program Results

Program Results (g05tlce.r)

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

© The Numerical Algorithms Group Ltd, Oxford, UK. 2014