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@stdlib/random-base-exponential
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Exponentially distributed pseudorandom numbers.
npm install @stdlib/random-base-exponential
var exponential = require( '@stdlib/random-base-exponential' );
Returns a pseudorandom number drawn from an exponential distribution with rate parameter lambda
.
var r = exponential( 7.9 );
// returns <number>
If lambda <= 0
or lambda
is NaN
, the function returns NaN
.
var r = exponential( -2.0 );
// returns NaN
r = exponential( NaN );
// returns NaN
Returns a pseudorandom number generator (PRNG) for generating pseudorandom numbers drawn from an exponential distribution.
var rand = exponential.factory();
var r = rand( 5.0 );
// returns <number>
If provided lambda
, the returned generator returns random variates from the specified distribution.
var rand = exponential.factory( 10.0 );
var r = rand();
// returns <number>
r = rand();
// returns <number>
If not provided lambda
, the returned generator requires that lambda
be provided at each invocation.
var rand = exponential.factory();
var r = rand( 4.0 );
// returns <number>
r = rand( 3.14 );
// returns <number>
The function accepts the following options
:
[0,1)
. If provided, the function ignores both the state
and seed
options. In order to seed the returned pseudorandom number generator, one must seed the provided prng
(assuming the provided prng
is seedable).Uint32Array
containing pseudorandom number generator state. If provided, the function ignores the seed
option.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 use a custom PRNG as the underlying source of uniformly distributed pseudorandom numbers, set the prng
option.
var minstd = require( '@stdlib/random-base-minstd' );
var rand = exponential.factory({
'prng': minstd.normalized
});
var r = rand( 3.0 );
// returns <number>
To seed a pseudorandom number generator, set the seed
option.
var rand1 = exponential.factory({
'seed': 12345
});
var r1 = rand1( 3.0 );
// returns <number>
var rand2 = exponential.factory( 3.0, {
'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 = exponential( 3.0 );
}
// Create a new PRNG initialized to the current state of `exponential`:
rand = exponential.factory({
'state': exponential.state
});
// Test that the generated pseudorandom numbers are the same:
bool = ( rand( 3.0 ) === exponential( 3.0 ) );
// returns true
The generator name.
var str = exponential.NAME;
// returns 'exponential'
The underlying pseudorandom number generator.
var prng = exponential.PRNG;
// returns <Function>
The value used to seed exponential()
.
var rand;
var r;
var i;
// Generate pseudorandom values...
for ( i = 0; i < 100; i++ ) {
r = exponential( 2.0 );
}
// Generate the same pseudorandom values...
rand = exponential.factory( 2.0, {
'seed': exponential.seed
});
for ( i = 0; i < 100; i++ ) {
r = rand();
}
If provided a PRNG for uniformly distributed numbers, this value is null
.
var rand = exponential.factory({
'prng': Math.random
});
var seed = rand.seed;
// returns null
Length of generator seed.
var len = exponential.seedLength;
// returns <number>
If provided a PRNG for uniformly distributed numbers, this value is null
.
var rand = exponential.factory({
'prng': Math.random
});
var len = rand.seedLength;
// returns null
Writable property for getting and setting the generator state.
var r = exponential( 7.9 );
// returns <number>
r = exponential( 7.9 );
// returns <number>
// ...
// Get a copy of the current state:
var state = exponential.state;
// returns <Uint32Array>
r = exponential( 7.9 );
// returns <number>
r = exponential( 7.9 );
// returns <number>
// Reset the state:
exponential.state = state;
// Replay the last two pseudorandom numbers:
r = exponential( 7.9 );
// returns <number>
r = exponential( 7.9 );
// returns <number>
// ...
If provided a PRNG for uniformly distributed numbers, this value is null
.
var rand = exponential.factory({
'prng': Math.random
});
var state = rand.state;
// returns null
Length of generator state.
var len = exponential.stateLength;
// returns <number>
If provided a PRNG for uniformly distributed numbers, this value is null
.
var rand = exponential.factory({
'prng': Math.random
});
var len = rand.stateLength;
// returns null
Size (in bytes) of generator state.
var sz = exponential.byteLength;
// returns <number>
If provided a PRNG for uniformly distributed numbers, this value is null
.
var rand = exponential.factory({
'prng': Math.random
});
var sz = rand.byteLength;
// returns null
Serializes the pseudorandom number generator as a JSON object.
var o = exponential.toJSON();
// returns { 'type': 'PRNG', 'name': '...', 'state': {...}, 'params': [] }
If provided a PRNG for uniformly distributed numbers, this method returns null
.
var rand = exponential.factory({
'prng': Math.random
});
var o = rand.toJSON();
// returns null
var exponential = require( '@stdlib/random-base-exponential' );
var seed;
var rand;
var i;
// Generate pseudorandom numbers...
for ( i = 0; i < 100; i++ ) {
console.log( exponential( 0.5 ) );
}
// Create a new pseudorandom number generator...
seed = 1234;
rand = exponential.factory( 0.8, {
'seed': seed
});
for ( i = 0; i < 100; i++ ) {
console.log( rand() );
}
// Create another pseudorandom number generator using a previous seed...
rand = exponential.factory( 0.5, {
'seed': exponential.seed
});
for ( i = 0; i < 100; i++ ) {
console.log( rand() );
}
@stdlib/random-array/exponential
: create an array containing pseudorandom numbers drawn from an exponential distribution.@stdlib/random-iter/exponential
: create an iterator for generating pseudorandom numbers drawn from an exponential distribution.@stdlib/random-streams/exponential
: create a readable stream for generating pseudorandom numbers drawn from an exponential distribution.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.
Copyright © 2016-2024. The Stdlib Authors.
FAQs
Exponentially distributed pseudorandom numbers.
The npm package @stdlib/random-base-exponential receives a total of 4,926 weekly downloads. As such, @stdlib/random-base-exponential popularity was classified as popular.
We found that @stdlib/random-base-exponential demonstrated a not healthy version release cadence and project activity because the last version was released a year ago. It has 4 open source maintainers collaborating on the project.
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