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Create an iterator for generating pseudorandom numbers drawn from a Laplace (double exponential) distribution.
npm install @stdlib/random-iter-laplace
Alternatively,
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tag without installation and bundlers, use the ES Module available on theesm
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branch (see README for usage intructions). - For use in Observable, or in browser/node environments, use the Universal Module Definition (UMD) build available on the
umd
branch (see README).
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To view installation and usage instructions specific to each branch build, be sure to explicitly navigate to the respective README files on each branch, as linked to above.
var iterator = require( '@stdlib/random-iter-laplace' );
Returns an iterator for generating pseudorandom numbers drawn from a Laplace (double exponential) distribution with parameters mu
(mean) and b
(scale).
var it = iterator( 2.0, 5.0 );
// returns <Object>
var r = it.next().value;
// returns <number>
r = it.next().value;
// returns <number>
r = it.next().value;
// returns <number>
// ...
If b <= 0
, the function throws an error.
var it = iterator( 1.0, -1.0 );
// throws <TypeError>
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 pseudorandom number generator state. Default:true
. - iter: number of iterations.
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 it = iterator( 2.0, 4.0, {
'prng': minstd.normalized
});
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( 2.0, 4.0 );
// 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( 2.0, 4.0, {
'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( 2.0, 4.0, {
'seed': 12345
});
var r1 = it1.next().value;
// returns <number>
var it2 = iterator( 2.0, 4.0, {
'seed': 12345
});
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( 2.0, 4.0, {
'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 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.
- seed: pseudorandom number generator seed. If provided a
prng
option, the property value isnull
. - seedLength: length of generator seed. If provided a
prng
option, the property value isnull
. - state: writable property for getting and setting the generator state. If provided a
prng
option, the property value isnull
. - stateLength: length of generator state. If provided a
prng
option, the property value isnull
. - byteLength: size (in bytes) of generator state. If provided a
prng
option, the property value isnull
. - PRNG: underlying pseudorandom number generator.
- If an environment supports
Symbol.iterator
, the returned iterator is iterable. - If PRNG state is "shared" (meaning a state array was provided during iterator creation and not copied) and one sets the underlying generator 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 the output of the underlying generator according to the new shared state array, the state array for each relevant iterator 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 iterator and/or PRNGs sharing the PRNG's state array).
var iterator = require( '@stdlib/random-iter-laplace' );
var it;
var r;
// Create a seeded iterator for generating pseudorandom numbers:
it = iterator( -1.0, 3.0, {
'seed': 1234,
'iter': 10
});
// Perform manual iteration...
while ( true ) {
r = it.next();
if ( r.done ) {
break;
}
console.log( r.value );
}
@stdlib/random-base/laplace
: Laplace (double exponential) distributed pseudorandom numbers.
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