# rgammatr: Random generator for a Truncated Gamma distribution. In RGeode: Geometric Density Estimation

## Description

Simulate random number from a truncated Gamma distribution.

## Usage

 `1` ```rgammatr(n = 1, A = 0, B = 1, range = NULL) ```

## Arguments

 `n` int, optional number of simulations. `A` double, optional shape parameter of the distribution. `B` double, optional rate parameter of the distribution. `range` array_like, optional domain of the distribution, where we truncate our Gamma. range(0) is the min of the range and range(1) is the max of the range.

## Details

It provide a way to simulate from a truncated Gamma distribution with given pameters A,B and range range. This will be used during the posterior sampling in th Gibbs sampler.

## Value

`rgammatr` returns the simulated value of the distribution:

 `u` double it is the simulated value of the truncated Gamma distribution. It will be a value in (range(0),range(1)).

## Author(s)

L. Rimella, lorenzo.rimella@hotmail.it

## References

• [1] Y. Wang, A. Canale, D. Dunson. "Scalable Geometric Density Estimation" (2016).
The implementation of rgammatr is inspired to the Matlab implementation of gamrndtruncated by Ye Wang.

## Examples

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23``` ```#Simulate a truncated Gamma with parameters 1,2 in the range #1,5. #Set the range: range<- c(1,5) #Simulate the truncated Gamma set.seed(123) vars1<-rgammatr(1000,1,2,range) #Look at the histogram hist(vars1,freq=FALSE,ylim=c(0,2),xlim = c(0,5)) lines(density(vars1)) #Compare with a non truncated Gamma set.seed(123) vars2<-rgamma(1000,1,2) #Compare the two results lines(density(vars2),col='red') #Observation: simulate without range is equivalent to simulate from #rgamma(1000,1,2) ```

RGeode documentation built on May 2, 2019, 1:09 p.m.