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Uniformly distributed pseudorandom numbers between 0 and 1.
To use in Observable,
randu = require( 'https://cdn.jsdelivr.net/gh/stdlib-js/random-base-randu@umd/browser.js' )
To vendor stdlib functionality and avoid installing dependency trees for Node.js, you can use the UMD server build:
var randu = require( 'path/to/vendor/umd/random-base-randu/index.js' )
To include the bundle in a webpage,
<script type="text/javascript" src="https://cdn.jsdelivr.net/gh/stdlib-js/random-base-randu@umd/browser.js"></script>
If no recognized module system is present, access bundle contents via the global scope:
<script type="text/javascript">
(function () {
window.randu;
})();
</script>
Returns a uniformly distributed pseudorandom number on the interval [0,1)
.
var r = randu();
// returns <number>
Returns a pseudorandom number generator (PRNG) for generating uniformly distributed random numbers on the interval [0,1)
.
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
: 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 tofalse
allows sharing state between two or more pseudorandom number generators. Setting this option totrue
ensures that a returned generator has exclusive control over its internal state. Default:true
.
By default, the underlying pseudorandom number generator is mt19937
. To use a different PRNG, set the name
option.
var rand = randu.factory({
'name': 'minstd-shuffle'
});
var r = rand();
// returns <number>
To seed a pseudorandom number generator, set the seed
option.
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.
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
The generator name.
var str = randu.NAME;
// returns 'randu'
The underlying pseudorandom number generator.
var prng = randu.PRNG;
// returns <Function>
Minimum value lower bound.
var min = randu.MIN;
// returns 0.0
Maximum value upper bound (not greater than 1
exclusive).
var max = randu.MAX;
// returns <number>
The value used to seed randu()
.
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();
}
Length of generator seed.
var len = randu.seedLength;
// returns <number>
Writable property for getting and setting the generator state.
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>
// ...
Length of generator state.
var len = randu.stateLength;
// returns <number>
Size (in bytes) of generator state.
var sz = randu.byteLength;
// returns <number>
Serializes the pseudorandom number generator as a JSON object.
var o = randu.toJSON();
// returns { 'type': 'PRNG', 'name': '...', 'state': {...}, 'params': [] }
- 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).
<!DOCTYPE html>
<html lang="en">
<body>
<script type="text/javascript" src="https://cdn.jsdelivr.net/gh/stdlib-js/random-base-randu@umd/browser.js"></script>
<script type="text/javascript">
(function () {
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() );
}
})();
</script>
</body>
</html>
@stdlib/random-array/randu
: create an array containing uniformly distributed pseudorandom numbers between 0 and 1.@stdlib/random-iter/randu
: create an iterator for generating uniformly distributed pseudorandom numbers between 0 and 1.@stdlib/random-streams/randu
: create a readable stream for generating uniformly distributed pseudorandom numbers between 0 and 1.@stdlib/random-base/discrete-uniform
: discrete uniform distributed pseudorandom numbers.@stdlib/random-base/randn
: standard normal pseudorandom numbers.
This package is part of stdlib, a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.
For more information on the project, filing bug reports and feature requests, and guidance on how to develop stdlib, see the main project repository.
See LICENSE.
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