randu

Usage

var iterator = require( '@stdlib/random/iter/randu' );

iterator( [options] )

Returns an iterator for generating uniformly distributed pseudorandom numbers between 0 and 1.

var it = iterator();
// returns <Object>

var r = it.next().value;
// returns <number>

r = it.next().value;
// returns <number>

r = it.next().value;
// returns <number>

// ...

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: 32-bit Mersenne Twister.
  • minstd: linear congruential pseudorandom number generator (LCG) based on Park and Miller.
  • minstd-shuffle: linear congruential pseudorandom number generator (LCG) whose output is shuffled.

  Default: '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.

• iter: number of iterations.

By default, the underlying pseudorandom number generator is mt19937. To use a different PRNG, set the name option.

var it = iterator({
    'name': 'minstd-shuffle'
});

var r = it.next().value;
// returns <number>

To return an iterator having a specific initial state, set the iterator state option.

var bool;
var it1;
var it2;
var r;
var i;

it1 = iterator();

// Generate pseudorandom numbers, thus progressing the generator state:
for ( i = 0; i < 1000; i++ ) {
    r = it1.next().value;
}

// Create a new iterator initialized to the current state of `it1`:
it2 = iterator({
    'state': it1.state
});

// Test that the generated pseudorandom numbers are the same:
bool = ( it1.next().value === it2.next().value );
// returns true

To seed the iterator, set the seed option.

var it1 = iterator({
    'seed': 7823
});

var r1 = it1.next().value;
// returns <number>

var it2 = iterator({
    'seed': 7823
});

var r2 = it2.next().value;
// returns <number>

var bool = ( r1 === r2 );
// returns true

To limit the number of iterations, set the iter option.

var it = iterator({
    'iter': 2
});

var r = it.next().value;
// returns <number>

r = it.next().value;
// returns <number>

r = it.next().done;
// returns true

The returned iterator protocol-compliant object has the following properties:

• next: function which returns an iterator protocol-compliant object containing the next iterated value (if one exists) assigned to a value property and a done property having a boolean value indicating whether the iterator is finished.
• return: function which closes an iterator and returns a single (optional) argument in an iterator protocol-compliant object.
• seed: pseudorandom number generator seed.
• seedLength: length of generator seed.
• state: writable property for getting and setting the generator state.
• stateLength: length of generator state.
• byteLength: size (in bytes) of generator state.
• PRNG: underlying pseudorandom number generator.