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iterawln
Create an iterator which introduces additive white Laplacian noise (AWLN).
Installation
npm install @stdlib/simulate-iter-awln
Usage
var iterawln = require( '@stdlib/simulate-iter-awln' );
iterawln( iterator, sigma[, options] )
Returns an iterator which introduces additive white Laplacian (a.k.a. biexponential or double-exponential) noise (AWLN) with standard deviation sigma
.
var array2iterator = require( '@stdlib/array-to-iterator' );
var arr = array2iterator( [ 1.0, 1.0, 1.0, 1.0, 1.0 ] );
var it = iterawln( arr, 0.2 );
var v = it.next().value;
// returns <number>
v = it.next().value;
// returns <number>
// ...
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 adone
property having aboolean
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.
- PRNG: underlying pseudorandom number generator (PRNG).
-
seed: pseudorandom number generator seed. If provided a PRNG, the property value is
null
. -
seedLength: length of generator seed. If provided a PRNG, the property value is
null
. -
state: pseudorandom number generator state. If provided a PRNG, the property value is
null
. -
stateLength: length of generator state. If provided a PRNG, the property value is
null
. -
byteLength: size (in bytes) of generator state. If provided a PRNG, the property value is
null
.
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 returned iterator, 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 a returned iterator has exclusive control over its internal state. Default:true
.
By default, an iterator uses the MT19937 algorithm to generate uniformly distributed pseudorandom numbers on the interval [0,1)
. To use a different PRNG, set the prng
option.
var array2iterator = require( '@stdlib/array-to-iterator' );
var minstd = require( '@stdlib/random-base-minstd-shuffle' );
var arr = array2iterator( [ 1.0, 1.0, 1.0, 1.0, 1.0 ] );
var it = iterawln( arr, 0.2, {
'prng': minstd.normalized
});
var v = it.next().value;
// returns <number>
To seed an iterator, set the seed
option.
var array2iterator = require( '@stdlib/array-to-iterator' );
var arr = array2iterator( [ 1.0, 1.0, 1.0, 1.0, 1.0 ] );
var it1 = iterawln( arr, 0.2, {
'seed': 12345
});
var v1 = it1.next().value;
// returns <number>
var it2 = iterawln( arr, 0.2, {
'seed': 12345
});
var v2 = it2.next().value;
// returns <number>
var bool = ( v1 === v2 );
// returns true
To return an iterator having a specific initial state, set the iterator state
option.
var array2iterator = require( '@stdlib/array-to-iterator' );
var arr = array2iterator( [ 1.0, 1.0, 1.0, 1.0, 1.0 ] );
var it1 = iterawln( arr, 0.2 );
// Progress the underlying generator state:
var i;
for ( i = 0; i < 3; i++ ) {
it1.next();
}
// Create a new iterator initialized to the current state of `it1`:
var it2 = iterawln( arr, 0.2, {
'state': it1.state
});
// Test that the iterator values are the same:
var bool = ( it1.next().value === it2.next().value );
// returns true
Notes
- If PRNG state is "shared" (meaning a state array was provided during iterator creation and not copied) and one sets the iterator state to a state array having a different length, the iterator does not update the existing shared state and, instead, points to the newly provided state array. In order to synchronize generated output according to the new shared state array, the state array for each relevant PRNG/iterator must be explicitly set.
- If PRNG state is "shared" and one sets the iterator state to a state array of the same length, the PRNG state is updated (along with the state of all other PRNGs/iterators sharing the state array).
- If an iterated value is non-numeric (including
NaN
), the returnediterator
returnsNaN
. If non-numeric iterated values are possible, you are advised to provide aniterator
which type checks and handles non-numeric values accordingly.
Examples
var iterSineWave = require( '@stdlib/simulate-iter-sine-wave' );
var iterawln = require( '@stdlib/simulate-iter-awln' );
// Create an iterator for generating a sine wave:
var sine = iterSineWave({
'iter': 100,
'amplitude': 10.0
});
// Create an iterator for introducing additive white Laplacian noise:
var it = iterawln( sine, 3.0 );
// Perform manual iteration...
var v;
while ( true ) {
v = it.next();
if ( v.done ) {
break;
}
console.log( v.value );
}
See Also
-
@stdlib/simulate-iter/awgn
: create an iterator which introduces additive white Gaussian noise. -
@stdlib/simulate-iter/awun
: create an iterator which introduces additive white uniform noise.
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.