urlogis {Runuran}

UNU.RAN Logistic random variate generator

Description

UNU.RAN random variate generator for the Logistic distribution with parameters location and scale. It also allows sampling from the truncated distribution.

[Special Generator] – Sampling Function: Logistic.

Usage

urlogis(n, location=0, scale=1, lb=-Inf, ub=Inf)

Arguments

n

size of required sample.

location

location parameter.

scale

(strictly positive) scale parameter.

lb

lower bound of (truncated) distribution.

ub

upper bound of (truncated) distribution.

Details

If location or scale are omitted, they assume the default values of 0 and 1 respectively.

The Logistic distribution with location = \mu and scale = \sigma has distribution function

F(x) = \frac{1}{1 + e^{-(x-\mu)/\sigma}}%

and density

f(x)= \frac{1}{\sigma}\frac{e^{(x-\mu)/\sigma}}{(1 + e^{(x-\mu)/\sigma})^2}%

The generation algorithm uses inversion. The parameters lb and ub can be used to generate variates from the Logistic distribution truncated to the interval (lb,ub).

Note

This function is a wrapper for the UNU.RAN class in R. Compared to rlogis, urlogis is faster, especially for larger sample sizes. However, in opposition to rlogis vector arguments are ignored, i.e. only the first entry is used.

Author(s)

Josef Leydold and Wolfgang H\"ormann [e-mail].

References

W. H\"ormann, J. Leydold, and G. Derflinger (2004): Automatic Nonuniform Random Variate Generation. Springer-Verlag, Berlin Heidelberg

See Also

runif and .Random.seed about random number generation, unuran for the UNU.RAN class, and rlogis for the R built-in generator.

Examples

## Create a sample of size 1000
x <- urlogis(n=1000)