R: The inverse Weibull distribution

inverseWeibull

R Documentation

The inverse Weibull distribution

Description

Density function, distribution function, quantile function, random generation, raw moments and limited moments for the Inverse Weibull distribution with parameters shape and scale.

Usage

dinvweibull(x, shape, scale = 1, log = FALSE)
pinvweibull(q, shape, scale = 1, lower.tail = TRUE, log.p = FALSE)
qinvweibull(p, shape, scale = 1, lower.tail = TRUE, log.p = FALSE)
rinvweibull(n, shape, scale = 1)

Arguments

`x, q`	vector of quantiles.
`p`	vector of probabilities.
`n`	number of observations. If `length(n) > 1`, the length is taken to be the number required.
`shape, scale`	parameters. Must be positive.
`log, log.p`	logical; if `TRUE`, probabilities or densities p are given as log(p).
`lower.tail`	logical; if `TRUE` (default), probabilities are P[X <= x], otherwise, P[X > x].

Details

The probability density function of the inverse Weibull distribution with parameters shape =b and scale =s is given by

f(x) = b (s/x)^b exp(-(s/x)^b)/x

where x > 0, b > 0 and s > 0.

The cumulative distribution function is given by

F(x) = exp(-(s/x)^b)

Value

dinvweibull gives the density, pinvweibull gives the distribution function, qinvweibull gives the quantile function, and rinvweibull generates random deviates.

Author(s)

Chanseok Park

Examples

x = (-1):2
names(x) = letters[1:4]
dinvweibull(x, shape=2) 
exp( dinvweibull(x, shape=2, log=TRUE) )


pinvweibull (1, shape=2)
exp(pinvweibull (1, shape=2,  log=TRUE))

q = c(-1,0,1,2)
qinvweibull ( pinvweibull (q, shape=2), shape=2 )