# RandPCG
A random number generator using the [PCG](http://www.pcg-random.org/) algorithm.
Documentation: https://hexdocs.pm/rand_pcg/
## Installation
1. Add `rand_pcg` to your list of dependencies in `mix.exs`:
```elixir
def deps do
[{:rand_pcg, "~> 0.1.2"}]
end
```
2. If you are using the GenServer option, ensure `rand_pcg` is started before
your application:
```elixir
def application do
[applications: [:rand_pcg]]
end
```
## Examples
### GenServer Option
#### Get Some Random
```elixir
# Random 32 bit integer
RandPCG.random()
# Random 32 bit based float
RandPCG.random(:float)
# n Random 32 bit integers
RandPCG.random(n)
# Random nth of an enumerable
list = [:a, :b, :c]
RandPCG.random(list)
# Random integer x where min <= x <= max
RandPCG.random(min, max)
# n random integers x where min <= x <= max
RandPCG.random(min, max, n)
```
#### Set State
```elixir
state = %RandPCG.State{seed: 234532454323451, inc: 1}
RandPCG.state(state)
```
#### Note
The initial seed is based on `:os.system_time(:micro_seconds)`
### Without running the GenServer
You will have to maintain your own state of the random number generator.
#### Random 32 bit Integer
```elixir
state = RandPCG.PCG.gen_state()
random_int_32 = RandPCG.PCG.xsh_rr(state)
state = advance(state)
```
If you do not advance the state, you will receive the same random number.
#### Random Integer in a Range
```elixir
state = RandPCG.PCG.gen_state()
min = 1
max = 10
random_1_10_inclusive = RandPCG.PCG.rand_int(min, max, state)
state = advance(state)
```
`RandPCG.PCG.gen_state` initial seed is based on `:os.system_time(:micro_seconds)`
## References
- [PCG Random Number Generator Homepage](http://www.pcg-random.org/)
- [PCG Basic C Implementation](https://github.com/imneme/pcg-c-basic)
- [PCG Go Implementation](https://github.com/dgryski/go-pcgr) was also helpful