Runuran.distributions: UNU.RAN distribution objects
In Runuran: R Interface to the 'UNU.RAN' Random Variate Generators

Runuran.distributions

R Documentation

UNU.RAN distribution objects

Description

Create objects for particular distributions suitable for using with generation methods from the UNU.RAN library.

Details

Runuran provides an interface to the UNU.RAN library for universal non-uniform random number generators. This is a very flexible and powerful collection of sampling routines, where the user first has to specify the target distribution and then has to choose an appropriate sampling method.

Creating an object for a particular distribution can be a bit tedious especially if the target distribution has a more complex density function. Thus we have compiled a set of functions that provides ready-to-use distribution objects. Moreover, using these object often results in faster setup time than objects created with pure R code.

These functions share a similar syntax and naming scheme (only ud is prefixed) with analogous R built-in functions that provide density, distribution function and quantile:

ud...(distribution parameters, lb , ub)

Currently generators for the following distributions are implemented.

Continuous Univariate Distributions (26):

Function		Distribution
`udbeta`	...	Beta
`udcauchy`	...	Cauchy
`udchi`	...	Chi
`udchisq`	...	Chi-squared
`udexp`	...	Exponential
`udf`	...	F
`udfrechet`	...	Frechet (Extreme value type II)
`udgamma`	...	Gamma
`udghyp`	...	Generalized Hyperbolic
`udgig`	...	Generalized Inverse Gaussian
`udgumbel`	...	Gumbel (Extreme value type I)
`udhyperbolic`	...	Hyperbolic
`udig`	...	Inverse Gaussian (Wald)
`udlaplace`	...	Laplace (double exponential)
`udlnorm`	...	Log Normal
`udlogis`	...	Logistic
`udlomax`	...	Lomax (Pareto of second kind)
`udmeixner`	...	Meixner
`udnorm`	...	Normal (Gaussian)
`udpareto`	...	Pareto (of first kind)
`udpowerexp`	...	Powerexponential (Subbotin)
`udrayleigh`	...	Rayleigh
`udslash`	...	Slash
`udt`	...	t (Student)
`udvg`	...	Variance Gamma
`udweibull`	...	Weibull (Extreme value type III)

Discrete Distributions (6):

Function		Distribution
`udbinom`	...	Binomial
`udgeom`	...	Geometric
`udhyper`	...	Hypergeometric
`udlogarithmic`	...	Logarithmic
`udnbinom`	...	Negative Binomial
`udpois`	...	Poisson

Author(s)

Josef Leydold and Wolfgang H\"ormann unuran@statmath.wu.ac.at.

Examples

## Create an object for a gamma distribution with shape parameter 5.
distr <- udgamma(shape=5)
## Create the UNU.RAN generator object. use method PINV (inversion).
gen <- pinvd.new(distr)
## Draw a sample of size 100
x <- ur(gen, 100)
## Compute some quantiles for Monte Carlo methods
x <- uq(gen, (1:9)/10)

## Analogous for half normal distribution
distr <- udnorm(lb=0, ub=Inf)
gen <- pinvd.new(distr)
x <- ur(gen, 100)
x <- uq(gen, (1:9)/10)

## Analogous for a generalized hyperbolic distribution
distr <- udghyp(lambda=-1.0024, alpha=39.6, beta=4.14, delta=0.0118, mu=-0.000158)
gen <- pinvd.new(distr)
x <- ur(gen, 100)
x <- uq(gen, (1:9)/10)

## It is also possible to compute density or distribution functions.
## However, this might not work for all generator objects.
##    Density
x <- ud(gen, 1.2)
##    Cumulative distribution function
x <- up(gen, 1.2)

Runuran documentation built on Jan. 17, 2023, 5:17 p.m.