Document property and options

Author: kgryte

lib/node_modules/@stdlib/random/base/erlang/README.md

@@ -102,6 +102,8 @@ r = rand( 4, 3.14 );
 The function accepts the following `options`:
 
 -   **seed**: pseudorandom number generator seed.
+-   **state**: a [`Uint32Array`][@stdlib/array/uint32] containing pseudorandom number generator state. If provided, the function ignores the `seed` option.
+-   **copy**: `boolean` indicating whether to copy a provided pseudorandom number generator state. Setting this option to `false` allows sharing state between two or more pseudorandom number generators. Setting this option to `true` ensures that a returned generator has exclusive control over its internal state. Default: `true`.
 
 To seed a pseudorandom number generator, set the `seed` option.
 
@@ -124,6 +126,29 @@ var bool = ( r1 === r2 );
 // returns true
 ```
 
+To return a generator having a specific initial state, set the generator `state` option.
+
+```javascript
+var rand;
+var bool;
+var r;
+var i;
+
+// Generate pseudorandom numbers, thus progressing the generator state:
+for ( i = 0; i < 1000; i++ ) {
+    r = erlang( 2, 3.0 );
+}
+
+// Create a new PRNG initialized to the current state of `erlang`:
+rand = erlang.factory({
+    'state': erlang.state
+});
+
+// Test that the generated pseudorandom numbers are the same:
+bool = ( rand( 2, 3.0 ) === erlang( 2, 3.0 ) );
+// returns true
+```
+
 #### erlang.NAME
 
 The generator name.
@@ -165,6 +190,15 @@ for ( i = 0; i < 100; i++ ) {
 }
 ```
 
+#### erlang.seedLength
+
+Length of generator seed.
+
+```javascript
+var len = erlang.seedLength;
+// returns <number>
+```
+
 #### erlang.state
 
 Writable property for getting and setting the generator state.
@@ -223,6 +257,17 @@ var sz = erlang.byteLength;
 
 <!-- /.usage -->
 
+<section class="notes">
+
+## Notes
+
+-   If PRNG state is "shared" (meaning a state array was provided during PRNG creation and **not** copied) and one sets the generator state to a state array having a different length, the PRNG does **not** update the existing shared state and, instead, points to the newly provided state array. In order to synchronize PRNG output according to the new shared state array, the state array for **each** relevant PRNG must be **explicitly** set.
+-   If PRNG state is "shared" and one sets the generator state to a state array of the same length, the PRNG state is updated (along with the state of all other PRNGs sharing the PRNG's state array).
+
+</section>
+
+<!-- /.notes -->
+
 <section class="examples">
 
 ## Examples
@@ -267,6 +312,8 @@ for ( i = 0; i < 100; i++ ) {
 
 [erlang]: https://en.wikipedia.org/wiki/Erlang_distribution
 
+[@stdlib/array/uint32]: https://github.com/stdlib-js/stdlib
+
 </section>
 
 <!-- /.links -->