rbeta {rBeta2009}

The Beta Random Number Generating Function

Description

Random generation for the beta distribution with parameters shape1 and shape2.

Usage

 rbeta(n, shape1, shape2)

Arguments

n

Number of beta random numbers to generate. If length(n) > 1, the length is taken to be the number required.

shape1, shape2

Positive shape parameters.

Details

The beta distribution with parameters shape1 = a and shape2 = b has density

\frac{\Gamma(a+b)}{\Gamma(a)\Gamma(b)} x^{a-1} (1-x)^{b-1}

for a > 0, b > 0 and 0 \le x \le 1.

The mean is \frac{a}{a+b} and the variance is \frac{ab}{(a+b)^2 (a+b+1)}.

rbeta basically utilizes the following guideline primarily proposed by Hung et al. (2009) for generating beta random numbers.

• When max(shape1, shape2) < 1, the B00 algorithm (Sakasegawa, 1983) is used;

• When shape1 < 1 < shape2 or shape1 > 1 > shape2, the B01 algorithm (Sakasegawa, 1983) is used;

• When min(shape1, shape1) > 1, the B4PE algorithm (Schmeiser and Babu, 1980) is used if one papameter is close to 1 and the other is large (say > 4); otherwise, the BPRS algorithm (Zechner and Stadlober, 1993) is used.

Value

rbeta generates beta random numbers.

Author(s)

Ching-Wei Cheng <[e-mail]>,
Ying-Chao Hung <[e-mail]>,
Narayanaswamy Balakrishnan <[e-mail]>

Source

rbeta uses a C translation of

Y. C. Hung and N. Balakrishnan and Y. T. Lin (2009), Evaluation of beta generation algorithms, Communications in Statistics - Simulation and Computation, 38:750–770.

References

Y. C. Hung and N. Balakrishnan and Y. T. Lin (2009), Evaluation of beta generation algorithms, Communications in Statistics - Simulation and Computation, 38, 750–770.

H. Sakasegawa (1983), Stratified rejection and squeeze method for generating beta random numbers, Annals of the Institute Statistical Mathematics, 35, 291–302.

B.W. Schmeiser and A.J.G. Babu (1980), Beta variate generation via exponential majorizing functions, Operations Research, 28, 917–926.

H. Zechner and E. Stadlober (1993), Generating beta variates via patchwork rejection, Computing, 50, 1–18.

See Also

rbeta in package stats.

Examples

 library(rBeta2009)
 rbeta(10, 0.7, 1.5)