About stdlib...
We believe in a future in which the web is a preferred environment for numerical computation. To help realize this future, we've built stdlib. stdlib is a standard library, with an emphasis on numerical and scientific computation, written in JavaScript (and C) for execution in browsers and in Node.js.
The library is fully decomposable, being architected in such a way that you can swap out and mix and match APIs and functionality to cater to your exact preferences and use cases.
When you use stdlib, you can be absolutely certain that you are using the most thorough, rigorous, well-written, studied, documented, tested, measured, and high-quality code out there.
To join us in bringing numerical computing to the web, get started by checking us out on GitHub, and please consider financially supporting stdlib. We greatly appreciate your continued support!
Gumbel Random Numbers
Create an array containing pseudorandom numbers drawn from a Gumbel distribution.
Installation
npm install @stdlib/random-array-gumbel
Usage
var gumbel = require( '@stdlib/random-array-gumbel' );
gumbel( len, mu, beta[, options] )
Returns an array containing pseudorandom numbers drawn from a Gumbel distribution.
var out = gumbel( 10, 2.0, 5.0 );
// returns <Float64Array>
The function has the following parameters:
- len: output array length.
- mu: mean.
- beta: scale parameter.
- options: function options.
The function accepts the following options
:
-
dtype: output array data type. Must be a real-valued floating-point data type or "generic". Default:
'float64'
.
By default, the function returns a Float64Array
. To return an array having a different data type, set the dtype
option.
var opts = {
'dtype': 'generic'
};
var out = gumbel( 10, 2.0, 5.0, opts );
// returns [...]
gumbel.assign( mu, beta, out )
Fills an array with pseudorandom numbers drawn from a Gumbel distribution.
var zeros = require( '@stdlib/array-zeros' );
var x = zeros( 10, 'float64' );
// returns <Float64Array>
var out = gumbel.assign( 2.0, 5.0, x );
// returns <Float64Array>
var bool = ( out === x );
// returns true
The function has the following parameters:
- mu: mean.
- beta: scale parameter.
- out: output array.
gumbel.factory( [mu, beta, ][options] )
Returns a function for creating arrays containing pseudorandom numbers drawn from a Gumbel distribution.
var random = gumbel.factory();
var out = random( 10, 2.0, 5.0 );
// returns <Float64Array>
var len = out.length;
// returns 10
If provided distribution parameters, the returned generator returns random variates from the specified distribution.
var random = gumbel.factory( 2.0, 5.0 );
var out = random( 10 );
// returns <Float64Array>
out = random( 10 );
// returns <Float64Array>
If not provided distribution parameters, the returned generator requires that distribution parameters be provided at each invocation.
var random = gumbel.factory();
var out = random( 10, 2.0, 5.0 );
// returns <Float64Array>
out = random( 10, 2.0, 5.0 );
// returns <Float64Array>
The function accepts the following options
:
-
prng: pseudorandom number generator for generating uniformly distributed pseudorandom numbers on the interval
[0,1)
. If provided, the function ignores both thestate
andseed
options. In order to seed the underlying pseudorandom number generator, one must seed the providedprng
(assuming the providedprng
is seedable). - seed: pseudorandom number generator seed.
-
state: a
Uint32Array
containing pseudorandom number generator state. If provided, the function ignores theseed
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 an underlying generator has exclusive control over its internal state. Default:true
. -
dtype: default output array data type. Must be a real-valued floating-point data type or "generic". Default:
'float64'
.
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 opts = {
'prng': minstd.normalized
};
var random = gumbel.factory( 2.0, 5.0, opts );
var out = random( 10 );
// returns <Float64Array>
To seed the underlying pseudorandom number generator, set the seed
option.
var opts = {
'seed': 12345
};
var random = gumbel.factory( 2.0, 5.0, opts );
var out = random( 10, opts );
// returns <Float64Array>
The returned function accepts the following options
:
- dtype: output array data type. Must be a real-valued floating-point data type or "generic". This overrides the default output array data type.
To override the default output array data type, set the dtype
option.
var random = gumbel.factory( 2.0, 5.0 );
var out = random( 10 );
// returns <Float64Array>
var opts = {
'dtype': 'generic'
};
out = random( 10, opts );
// returns [...]
gumbel.PRNG
The underlying pseudorandom number generator.
var prng = gumbel.PRNG;
// returns <Function>
gumbel.seed
The value used to seed the underlying pseudorandom number generator.
var seed = gumbel.seed;
// returns <Uint32Array>
If the factory
method is provided a PRNG for uniformly distributed numbers, the associated property value on the returned function is null
.
var minstd = require( '@stdlib/random-base-minstd-shuffle' ).normalized;
var random = gumbel.factory( 2.0, 5.0, {
'prng': minstd
});
var seed = random.seed;
// returns null
gumbel.seedLength
Length of underlying pseudorandom number generator seed.
var len = gumbel.seedLength;
// returns <number>
If the factory
method is provided a PRNG for uniformly distributed numbers, the associated property value on the returned function is null
.
var minstd = require( '@stdlib/random-base-minstd-shuffle' ).normalized;
var random = gumbel.factory( 2.0, 5.0, {
'prng': minstd
});
var len = random.seedLength;
// returns null
gumbel.state
Writable property for getting and setting the underlying pseudorandom number generator state.
var state = gumbel.state;
// returns <Uint32Array>
If the factory
method is provided a PRNG for uniformly distributed numbers, the associated property value on the returned function is null
.
var minstd = require( '@stdlib/random-base-minstd-shuffle' ).normalized;
var random = gumbel.factory( 2.0, 5.0, {
'prng': minstd
});
var state = random.state;
// returns null
gumbel.stateLength
Length of underlying pseudorandom number generator state.
var len = gumbel.stateLength;
// returns <number>
If the factory
method is provided a PRNG for uniformly distributed numbers, the associated property value on the returned function is null
.
var minstd = require( '@stdlib/random-base-minstd-shuffle' ).normalized;
var random = gumbel.factory( 2.0, 5.0, {
'prng': minstd
});
var len = random.stateLength;
// returns null
gumbel.byteLength
Size (in bytes) of underlying pseudorandom number generator state.
var sz = gumbel.byteLength;
// returns <number>
If the factory
method is provided a PRNG for uniformly distributed numbers, the associated property value on the returned function is null
.
var minstd = require( '@stdlib/random-base-minstd-shuffle' ).normalized;
var random = gumbel.factory( 2.0, 5.0, {
'prng': minstd
});
var sz = random.byteLength;
// returns null
Notes
- If PRNG state is "shared" (meaning a state array was provided during function creation and not copied) and one sets the underlying generator state to a state array having a different length, the function returned by the
factory
method does not update the existing shared state and, instead, points to the newly provided state array. In order to synchronize the output of the underlying generator according to the new shared state array, the state array for each relevant creation function and/or PRNG must be explicitly set. - If PRNG state is "shared" and one sets the underlying generator state to a state array of the same length, the PRNG state is updated (along with the state of all other creation functions and/or PRNGs sharing the PRNG's state array).
Examples
var logEach = require( '@stdlib/console-log-each' );
var gumbel = require( '@stdlib/random-array-gumbel' );
// Create a function for generating random arrays originating from the same state:
var random = gumbel.factory( 2.0, 5.0, {
'state': gumbel.state,
'copy': true
});
// Generate 3 arrays:
var x1 = random( 5 );
var x2 = random( 5 );
var x3 = random( 5 );
// Print the contents:
logEach( '%f, %f, %f', x1, x2, x3 );
// Create another function for generating random arrays with the original state:
random = gumbel.factory( 2.0, 5.0, {
'state': gumbel.state,
'copy': true
});
// Generate a single array which replicates the above pseudorandom number generation sequence:
var x4 = random( 15 );
// Print the contents:
logEach( '%f', x4 );
See Also
-
@stdlib/random-base/gumbel
: Gumbel distributed pseudorandom numbers.
Notice
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.
Community
License
See LICENSE.
Copyright
Copyright © 2016-2024. The Stdlib Authors.