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NAG Toolbox

NAG Toolbox: nag_rand_logical (g05tb)

 Contents

    1  Purpose
    2  Syntax
    7  Accuracy
    9  Example

Purpose

nag_rand_logical (g05tb) generates a vector of pseudorandom logical values – true with probability p and false with probability 1-p.

Syntax

[state, x, ifail] = g05tb(n, p, state)
[state, x, ifail] = nag_rand_logical(n, p, state)

Description

nag_rand_logical (g05tb) generates n logical values xi from the relation
yi<p  
where yi is a pseudorandom number from a uniform distribution over 0,1, generated by nag_rand_dist_uniform01 (g05sa) using the values of state as input to this function.
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_logical (g05tb).

References

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

Parameters

Compulsory Input Parameters

1:     n int64int32nag_int scalar
n, the number of pseudorandom logical values to be generated.
Constraint: n0.
2:     p – double scalar
Must contain the probability of nag_rand_logical (g05tb) returning true.
Constraint: 0.0p1.0.
3:     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

None.

Output Parameters

1:     state: int64int32nag_int array
Contains updated information on the state of the generator.
2:     xn – logical array
The n logical values.
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:
   ifail=1
Constraint: n0.
   ifail=2
Constraint: 0.0p1.0.
   ifail=3
On entry, state vector has been corrupted or not initialized.
   ifail=-99
An unexpected error has been triggered by this routine. Please contact NAG.
   ifail=-399
Your licence key may have expired or may not have been installed correctly.
   ifail=-999
Dynamic memory allocation failed.

Accuracy

Not applicable.

Further Comments

None.

Example

This example prints the first 20 pseudorandom logical values generated by nag_rand_logical (g05tb) after initialization by nag_rand_init_repeat (g05kf), when the probability of a true value is 0.5.
function g05tb_example


fprintf('g05tb 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(20);

% Parameters
p = 0.5;

% Generate variates from a logical distribution
[state, x, ifail] = g05tb( ...
                           n, p, state);

disp('Variates');
for i = 1:n
  if x(i)
    fprintf('    true\n');
  else
    fprintf('    false\n');
  end
end


g05tb example results

Variates
    false
    true
    false
    false
    true
    true
    true
    false
    true
    false
    true
    true
    false
    true
    false
    true
    true
    false
    false
    false

PDF version (NAG web site, 64-bit version, 64-bit version)
Chapter Contents
Chapter Introduction
NAG Toolbox

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