time-to-botec

README.md (7271B)

---

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 @license Apache-2.0
 
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 # randu
 
 > Uniformly distributed pseudorandom numbers between 0 and 1.
 
 <section class="usage">
 
 ## Usage
 
 ```javascript
 var randu = require( '@stdlib/random/base/randu' );
 ```
 
 #### randu()
 
 Returns a uniformly distributed pseudorandom number on the interval `[0,1)`.
 
 ```javascript
 var r = randu();
 // returns <number>
 ```
 
 #### randu.factory( \[options] )
 
 Returns a pseudorandom number generator (PRNG) for generating uniformly distributed random numbers on the interval `[0,1)`.
 
 ```javascript
 var rand = randu.factory();
 ```
 
 The function accepts the following `options`:
 
 -   **name**: name of a supported pseudorandom number generator (PRNG), which will serve as the underlying source of pseudorandom numbers. The following generators are supported:
 
     -   [`mt19937`][@stdlib/random/base/mt19937]: https://www.npmjs.com/package/@stdlib/random/tree/main/base/mt19937
     -   [`minstd`][@stdlib/random/base/minstd]: https://www.npmjs.com/package/@stdlib/random/tree/main/base/minstd
     -   [`minstd-shuffle`][@stdlib/random/base/minstd-shuffle]: https://www.npmjs.com/package/@stdlib/random/tree/main/base/minstd-shuffle
 
     Default: [`'mt19937'`][@stdlib/random/base/mt19937].
 
 -   **seed**: pseudorandom number generator seed. Valid seed values vary according to the underlying PRNG.
 
 -   **state**: pseudorandom number generator state. Valid state values vary according to the underlying PRNG. 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`.
 
 By default, the underlying pseudorandom number generator is [`mt19937`][@stdlib/random/base/mt19937]. To use a different PRNG, set the `name` option.
 
 ```javascript
 var rand = randu.factory({
     'name': 'minstd-shuffle'
 });
 
 var r = rand();
 // returns <number>
 ```
 
 To seed a pseudorandom number generator, set the `seed` option.
 
 ```javascript
 var rand1 = randu.factory({
     'seed': 12345
 });
 
 var r1 = rand1();
 // returns <number>
 
 var rand2 = randu.factory({
     'seed': 12345
 });
 
 var r2 = rand2();
 // returns <number>
 
 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 = randu();
 }
 
 // Create a new PRNG initialized to the current state of `randu`:
 rand = randu.factory({
     'state': randu.state
 });
 
 // Test that the generated pseudorandom numbers are the same:
 bool = ( rand() === randu() );
 // returns true
 ```
 
 #### randu.NAME
 
 The generator name.
 
 ```javascript
 var str = randu.NAME;
 // returns 'randu'
 ```
 
 #### randu.PRNG
 
 The underlying pseudorandom number generator.
 
 ```javascript
 var prng = randu.PRNG;
 // returns <Function>
 ```
 
 #### randu.MIN
 
 Minimum value lower bound.
 
 ```javascript
 var min = randu.MIN;
 // returns 0.0
 ```
 
 #### randu.MAX
 
 Maximum value upper bound (not greater than `1` exclusive).
 
 ```javascript
 var max = randu.MAX;
 // returns <number>
 ```
 
 #### randu.seed
 
 The value used to seed `randu()`.
 
 ```javascript
 var rand;
 var r;
 var i;
 
 // Generate pseudorandom values...
 for ( i = 0; i < 100; i++ ) {
     r = randu();
 }
 
 // Generate the same pseudorandom values...
 rand = randu.factory({
     'seed': randu.seed
 });
 for ( i = 0; i < 100; i++ ) {
     r = rand();
 }
 ```
 
 #### randu.seedLength
 
 Length of generator seed.
 
 ```javascript
 var len = randu.seedLength;
 // returns <number>
 ```
 
 #### randu.state
 
 Writable property for getting and setting the generator state.
 
 ```javascript
 var r = randu();
 // returns <number>
 
 r = randu();
 // returns <number>
 
 // ...
 
 // Get a copy of the current state:
 var state = randu.state;
 
 r = randu();
 // returns <number>
 
 r = randu();
 // returns <number>
 
 // Reset the state:
 randu.state = state;
 
 // Replay the last two pseudorandom numbers:
 r = randu();
 // returns <number>
 
 r = randu();
 // returns <number>
 
 // ...
 ```
 
 #### randu.stateLength
 
 Length of generator state.
 
 ```javascript
 var len = randu.stateLength;
 // returns <number>
 ```
 
 #### randu.byteLength
 
 Size (in bytes) of generator state.
 
 ```javascript
 var sz = randu.byteLength;
 // returns <number>
 ```
 
 #### randu.toJSON()
 
 Serializes the pseudorandom number generator as a JSON object.
 
 ```javascript
 var o = randu.toJSON();
 // returns { 'type': 'PRNG', 'name': '...', 'state': {...}, 'params': [] }
 ```
 
 </section>
 
 <!-- /.usage -->
 
 <section class="notes">
 
 ## Notes
 
 -   **Warning**: the default underlying source of pseudorandom numbers may **change** in the future. If exact reproducibility is required, either explicitly specify a PRNG via the `name` option or use an underlying PRNG directly.
 -   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
 
 <!-- eslint no-undef: "error" -->
 
 ```javascript
 var randu = require( '@stdlib/random/base/randu' );
 
 var seed;
 var rand;
 var i;
 
 // Generate pseudorandom numbers...
 for ( i = 0; i < 100; i++ ) {
     console.log( randu() );
 }
 
 // Create a new pseudorandom number generator...
 seed = 1234;
 rand = randu.factory({
     'seed': seed
 });
 for ( i = 0; i < 100; i++ ) {
     console.log( rand() );
 }
 
 // Create another pseudorandom number generator using a previous seed...
 rand = randu.factory({
     'seed': randu.seed
 });
 for ( i = 0; i < 100; i++ ) {
     console.log( rand() );
 }
 ```
 
 </section>
 
 <!-- /.examples -->
 
 <section class="links">
 
 [@stdlib/random/base/mt19937]: https://www.npmjs.com/package/@stdlib/random/tree/main/base/mt19937
 
 [@stdlib/random/base/minstd]: https://www.npmjs.com/package/@stdlib/random/tree/main/base/minstd
 
 [@stdlib/random/base/minstd-shuffle]: https://www.npmjs.com/package/@stdlib/random/tree/main/base/minstd-shuffle
 
 </section>
 
 <!-- /.links -->