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ForestFit (version 0.6.1)

rgsm: Simulating realizations from the gamma shape mixture model

Description

Simulates realizations from a gamma shape mixture (GSM) model with probability density function given by $$f(x,{\Theta}) = \sum_{j=1}^{K}\omega_j \frac{\beta^j}{\Gamma(j)} x^{j-1} \exp\bigl( -\beta x\bigr),$$ where \(\Theta=(\omega_1,\dots,\omega_K, \beta)^T\) is the parameter vector and known constant \(K\) is the number of components. The vector of mixing parameters is given by \(\omega=(\omega_1,\dots,\omega_K)^T\) where \(\omega_j\)s sum to one, i.e., \(\sum_{j=1}^{K}\omega_j=1\). Here \(\beta\) is the rate parameter that is equal for all components.

Usage

rgsm(n, omega, beta)

Arguments

n

Number of requested random realizations.

omega

Vector of the mixing parameters.

beta

The rate parameter.

Value

A vector of length n, giving random generated values from GSM model.

References

S. Venturini, F. Dominici, and G. Parmigiani, 2008. Gamma shape mixtures for heavy-tailed distributions, The Annals of Applied Statistics, 2(2), 756<U+2013>776.

Examples

Run this code
# NOT RUN {
n<-100
omega<-c(0.05, 0.1, 0.15, 0.2, 0.25, 0.25)
beta<-2
rgsm(n, omega, beta)
# }

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