---
title: "Radioactive Decay model (Gillespie, 1977)"
output: rmarkdown::html_vignette
vignette: >
  %\VignetteIndexEntry{Radioactive Decay model (Gillespie, 1977)}
  %\VignetteEncoding{UTF-8}
  %\VignetteEngine{knitr::rmarkdown}
editor_options: 
  chunk_output_type: console
---

<!-- github markdown built using 
rmarkdown::render("vignettes/radioactive_decay.Rmd", output_format = "github_document")
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```{r, setseed, echo=FALSE}
set.seed(1)
knitr::opts_chunk$set(fig.width = 6, fig.height = 4)
if("package:GillespieSSA" %in% search()) detach("package:GillespieSSA", unload=TRUE) 
```

This model is also known as the irreversible isomerization reaction set.
It consists of a single species and single reaction channels,
```
X --c--> 0
```

Define parameters
```{r}
library(GillespieSSA2)
sim_name <- "Radioactive Decay model"
params <- c(k = 0.5)
final_time <- 20
initial_state <- c(N = 1000)
```

Define reactions
```{r}
reactions <- list(
  reaction("k * N", c(N = -1))
)
```

Run simulations with the Exact method
```{r exact}
set.seed(1)
out <- ssa(
  initial_state = initial_state,
  reactions = reactions,
  params = params,
  final_time = final_time,
  method = ssa_exact(),
  sim_name = sim_name
) 
autoplot.ssa(out)
```

Run simulations with the Explict tau-leap method
```{r etl}
set.seed(1)
out <- ssa(
  initial_state = initial_state,
  reactions = reactions,
  params = params,
  final_time = final_time,
  method = ssa_etl(tau = .003),
  sim_name = sim_name
) 
autoplot.ssa(out)
```

Run simulations with the Binomial tau-leap method
```{r btl}
set.seed(1)
out <- ssa(
  initial_state = initial_state,
  reactions = reactions,
  params = params,
  final_time = final_time,
  method = ssa_btl(),
  sim_name = sim_name
) 
autoplot.ssa(out)
```
