stdlib-js
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</summary>
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Mersenne Twister
[![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url]
A 32-bit [Mersenne Twister][mersenne-twister] pseudorandom number generator.
bash
npm install @stdlib/random-base-mt19937
javascript
var mt19937 = require( '@stdlib/random-base-mt19937' );
#### mt19937()
Returns a pseudorandom integer on the interval [0, 4294967295].
javascript
var r = mt19937();
// returns <number>
#### mt19937.normalized()
Returns a pseudorandom number on the interval [0, 1) with 53-bit precision.
javascript
var r = mt19937.normalized();
// returns <number>
#### mt19937.factory( [options] )
Returns a 32-bit [Mersenne Twister][mersenne-twister] pseudorandom number generator.
javascript
var rand = mt19937.factory();
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.
By default, a random integer is used to seed the returned generator. To seed the generator, provide either an integer on the interval [0, 4294967295]
javascript
var rand = mt19937.factory({
'seed': 1234
});
var r = rand();
// returns 822569775
or, for arbitrary length seeds, an array-like object containing unsigned 32-bit integers
javascript
var Uint32Array = require( '@stdlib/array-uint32' );
var rand = mt19937.factory({
'seed': new Uint32Array( [ 291, 564, 837, 1110 ] )
});
var r = rand();
// returns 1067595299
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 = mt19937();
}
// Create a new MT19937 PRNG initialized to the current state of `mt19937`:
rand = mt19937.factory({
'state': mt19937.state
});
// Test that the generated pseudorandom numbers are the same:
bool = ( rand() === mt19937() );
// returns true
#### mt19937.NAME
The generator name.
javascript
var str = mt19937.NAME;
// returns 'mt19937'
#### mt19937.MIN
Minimum possible value.
javascript
var min = mt19937.MIN;
// returns 0
#### mt19937.MAX
Maximum possible value.
javascript
var max = mt19937.MAX;
// returns 4294967295
#### mt19937.seed
The value used to seed mt19937().
javascript
var rand;
var r;
var i;
// Generate pseudorandom values...
for ( i = 0; i < 100; i++ ) {
r = mt19937();
}
// Generate the same pseudorandom values...
rand = mt19937.factory({
'seed': mt19937.seed
});
for ( i = 0; i < 100; i++ ) {
r = rand();
}
#### mt19937.seedLength
Length of generator seed.
javascript
var len = mt19937.seedLength;
// returns <number>
#### mt19937.state
Writable property for getting and setting the generator state.
javascript
var r = mt19937();
// returns <number>
r = mt19937();
// returns <number>
// ...
// Get a copy of the current state:
var state = mt19937.state;
// returns <Uint32Array>
r = mt19937();
// returns <number>
r = mt19937();
// returns <number>
// Reset the state:
mt19937.state = state;
// Replay the last two pseudorandom numbers:
r = mt19937();
// returns <number>
r = mt19937();
// returns <number>
// ...
#### mt19937.stateLength
Length of generator state.
javascript
var len = mt19937.stateLength;
// returns <number>
#### mt19937.byteLength
Size (in bytes) of generator state.
javascript
var sz = mt19937.byteLength;
// returns <number>
#### mt19937.toJSON()
Serializes the pseudorandom number generator as a JSON object.
javascript
var o = mt19937.toJSON();
// returns { 'type': 'PRNG', 'name': '...', 'state': {...}, 'params': [] }
~2.5kB). Because of the large state size, beware of increased memory consumption when using the factory() method to create many [Mersenne Twister][mersenne-twister] PRNGs. When appropriate (e.g., when external state mutation is not a concern), consider sharing PRNG state.
- A seed array of length 1 is considered equivalent to an integer seed equal to the lone seed array element and vice versa.
- 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).
- The PRNG has a period of 2^19937 - 1.
javascript
var mt19937 = require( '@stdlib/random-base-mt19937' );
var seed;
var rand;
var i;
// Generate pseudorandom numbers...
for ( i = 0; i < 100; i++ ) {
console.log( mt19937() );
}
// Create a new pseudorandom number generator...
seed = 1234;
rand = mt19937.factory({
'seed': seed
});
for ( i = 0; i < 100; i++ ) {
console.log( rand() );
}
// Create another pseudorandom number generator using a previous seed...
rand = mt19937.factory({
'seed': mt19937.seed
});
for ( i = 0; i < 100; i++ ) {
console.log( rand() );
}
@stdlib/random-array/mt19937][@stdlib/random/array/mt19937]: create an array containing pseudorandom numbers generated using a 32-bit Mersenne Twister pseudorandom number generator.
- [@stdlib/random-iter/mt19937][@stdlib/random/iter/mt19937]: create an iterator for a 32-bit Mersenne Twister pseudorandom number generator.
- [@stdlib/random-streams/mt19937][@stdlib/random/streams/mt19937]: create a readable stream for a 32-bit Mersenne Twister pseudorandom number generator.
- [@stdlib/random-base/minstd][@stdlib/random/base/minstd]: A linear congruential pseudorandom number generator (LCG) based on Park and Miller.
- [@stdlib/random-base/randi][@stdlib/random/base/randi]: pseudorandom numbers having integer values.
