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Chapter Introduction
NAG Toolbox

NAG Toolbox: nag_rand_int_uniform (g05tl)


    1  Purpose
    2  Syntax
    7  Accuracy
    9  Example


nag_rand_int_uniform (g05tl) generates a vector of pseudorandom integers uniformly distributed over the interval a,b.


[state, x, ifail] = g05tl(n, a, b, state)
[state, x, ifail] = nag_rand_int_uniform(n, a, b, state)


nag_rand_int_uniform (g05tl) generates the next n values yi from a uniform 0,1 generator (see nag_rand_dist_uniform01 (g05sa) 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_repeat (g05kf) (for a repeatable sequence if computed sequentially) or nag_rand_init_nonrepeat (g05kg) (for a non-repeatable sequence) must be called prior to the first call to nag_rand_int_uniform (g05tl).


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


Compulsory Input Parameters

1:     n int64int32nag_int scalar
n, the number of pseudorandom numbers to be generated.
Constraint: n0.
2:     a int64int32nag_int scalar
3:     b int64int32nag_int scalar
The end points a and b of the uniform distribution.
Constraint: ab.
4:     state: int64int32nag_int array
Note: the actual argument supplied must be the array state supplied to the initialization routines nag_rand_init_repeat (g05kf) or nag_rand_init_nonrepeat (g05kg).
Contains information on the selected base generator and its current state.

Optional Input Parameters


Output Parameters

1:     state: int64int32nag_int array
Contains updated information on the state of the generator.
2:     xn int64int32nag_int array
The n pseudorandom numbers from the specified uniform distribution.
3:     ifail int64int32nag_int scalar
ifail=0 unless the function detects an error (see Error Indicators and Warnings).

Error Indicators and Warnings

Errors or warnings detected by the function:
Constraint: n0.
Constraint: ba.
On entry, state vector has been corrupted or not initialized.
An unexpected error has been triggered by this routine. Please contact NAG.
Your licence key may have expired or may not have been installed correctly.
Dynamic memory allocation failed.


Not applicable.

Further Comments



This example prints five pseudorandom integers from a discrete uniform distribution between -5 and 5, generated by a single call to nag_rand_int_uniform (g05tl), after initialization by nag_rand_init_repeat (g05kf).
function g05tl_example

fprintf('g05tl example results\n\n');

% Initialize the base generator to a repeatable sequence
seed  = [int64(1762543)];
genid = int64(1);
subid = int64(1);
[state, ifail] = g05kf( ...
                        genid, subid, seed);

% Number of variates
n = int64(5);

% Parameters
a = int64(-5);
b = int64(5);

% Generate integer variates from Uniform (a,b) distribution
[state, x, ifail] = g05tl( ...
                           n, a, b, state);


g05tl example results


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Chapter Introduction
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