NAG FL Interface
g05tbf (logical)

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1 Purpose

g05tbf generates a vector of pseudorandom logical values – .TRUE. with probability p and .FALSE. with probability (1-p).

2 Specification

Fortran Interface
Subroutine g05tbf ( n, p, state, x, ifail)
Integer, Intent (In) :: n
Integer, Intent (Inout) :: state(*), ifail
Real (Kind=nag_wp), Intent (In) :: p
Logical, Intent (Out) :: x(n)
C Header Interface
#include <nag.h>
void  g05tbf_ (const Integer *n, const double *p, Integer state[], logical x[], Integer *ifail)
The routine may be called by the names g05tbf or nagf_rand_logical.

3 Description

g05tbf generates n logical values xi from the relation
where yi is a pseudorandom number from a uniform distribution over (0,1], generated by g05saf using the values of state as input to this routine.
One of the initialization routines g05kff (for a repeatable sequence if computed sequentially) or g05kgf (for a non-repeatable sequence) must be called prior to the first call to g05tbf.

4 References

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

5 Arguments

1: n Integer Input
On entry: n, the number of pseudorandom logical values to be generated.
Constraint: n0.
2: p Real (Kind=nag_wp) Input
On entry: must contain the probability of g05tbf returning .TRUE..
Constraint: 0.0p1.0.
3: state(*) Integer array Communication Array
Note: the actual argument supplied must be the array state supplied to the initialization routines g05kff or g05kgf.
On entry: contains information on the selected base generator and its current state.
On exit: contains updated information on the state of the generator.
4: x(n) Logical array Output
On exit: the n logical values.
5: ifail Integer Input/Output
On entry: ifail must be set to 0, −1 or 1 to set behaviour on detection of an error; these values have no effect when no error is detected.
A value of 0 causes the printing of an error message and program execution will be halted; otherwise program execution continues. A value of −1 means that an error message is printed while a value of 1 means that it is not.
If halting is not appropriate, the value −1 or 1 is recommended. If message printing is undesirable, then the value 1 is recommended. Otherwise, the value 0 is recommended. When the value -1 or 1 is used it is essential to test the value of ifail on exit.
On exit: ifail=0 unless the routine detects an error or a warning has been flagged (see Section 6).

6 Error Indicators and Warnings

If on entry ifail=0 or −1, explanatory error messages are output on the current error message unit (as defined by x04aaf).
Errors or warnings detected by the routine:
On entry, n=value.
Constraint: n0.
On entry, p=value.
Constraint: 0.0p1.0.
On entry, state vector has been corrupted or not initialized.
An unexpected error has been triggered by this routine. Please contact NAG.
See Section 7 in the Introduction to the NAG Library FL Interface for further information.
Your licence key may have expired or may not have been installed correctly.
See Section 8 in the Introduction to the NAG Library FL Interface for further information.
Dynamic memory allocation failed.
See Section 9 in the Introduction to the NAG Library FL Interface for further information.

7 Accuracy

Not applicable.

8 Parallelism and Performance

Background information to multithreading can be found in the Multithreading documentation.
g05tbf is threaded by NAG for parallel execution in multithreaded implementations of the NAG Library.
Please consult the X06 Chapter Introduction for information on how to control and interrogate the OpenMP environment used within this routine. Please also consult the Users' Note for your implementation for any additional implementation-specific information.

9 Further Comments


10 Example

This example prints the first 20 pseudorandom logical values generated by g05tbf after initialization by g05kff, when the probability of a .TRUE. value is 0.5.

10.1 Program Text

Program Text (g05tbfe.f90)

10.2 Program Data

Program Data (g05tbfe.d)

10.3 Program Results

Program Results (g05tbfe.r)