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<!-- | ||
@license Apache-2.0 | ||
Copyright (c) 2024 The Stdlib Authors. | ||
Licensed under the Apache License, Version 2.0 (the "License"); | ||
you may not use this file except in compliance with the License. | ||
You may obtain a copy of the License at | ||
http://www.apache.org/licenses/LICENSE-2.0 | ||
Unless required by applicable law or agreed to in writing, software | ||
distributed under the License is distributed on an "AS IS" BASIS, | ||
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
See the License for the specific language governing permissions and | ||
limitations under the License. | ||
--> | ||
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# Bernoulli Random Numbers | ||
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> Fill a strided array with pseudorandom numbers drawn from a [Bernoulli][@stdlib/random/base/bernoulli] distribution. | ||
<section class="usage"> | ||
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## Usage | ||
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```javascript | ||
var bernoulli = require( '@stdlib/random/strided/bernoulli' ); | ||
``` | ||
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#### bernoulli( N, p, sp, out, so ) | ||
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Fills a strided array with pseudorandom numbers drawn from a [Bernoulli][@stdlib/random/base/bernoulli] distribution. | ||
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```javascript | ||
var Float64Array = require( '@stdlib/array/float64' ); | ||
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// Create an array: | ||
var out = new Float64Array( 10 ); | ||
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// Fill the array with pseudorandom numbers: | ||
bernoulli( out.length, [ 0.5 ], 0, out, 1 ); | ||
``` | ||
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The function has the following parameters: | ||
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- **N**: number of indexed elements. | ||
- **p**: rate parameter. | ||
- **sp**: index increment for `p`. | ||
- **out**: output array. | ||
- **so**: index increment for `out`. | ||
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The `N` and stride parameters determine which strided array elements are accessed at runtime. For example, to access every other value in `out`, | ||
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```javascript | ||
var out = [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ]; | ||
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bernoulli( 3, [ 0.5 ], 0, out, 2 ); | ||
``` | ||
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Note that indexing is relative to the first index. To introduce an offset, use [`typed array`][mdn-typed-array] views. | ||
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<!-- eslint-disable stdlib/capitalized-comments --> | ||
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```javascript | ||
var Float64Array = require( '@stdlib/array/float64' ); | ||
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// Initial array: | ||
var p0 = new Float64Array( [ 0.5, 0.5, 0.5, 0.5, 0.5, 0.5 ] ); | ||
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// Create offset view: | ||
var p1 = new Float64Array( p0.buffer, p0.BYTES_PER_ELEMENT*3 ); // start at 4th element | ||
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// Create an output array: | ||
var out = new Float64Array( 3 ); | ||
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// Fill the output array: | ||
bernoulli( out.length, p1, -1, out, 1 ); | ||
``` | ||
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#### bernoulli.ndarray( N, p, sp, op, out, so, oo ) | ||
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Fills a strided array with pseudorandom numbers drawn from a [Bernoulli][@stdlib/random/base/bernoulli] distribution using alternative indexing semantics. | ||
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```javascript | ||
var Float64Array = require( '@stdlib/array/float64' ); | ||
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// Create an array: | ||
var out = new Float64Array( 10 ); | ||
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// Fill the array with pseudorandom numbers: | ||
bernoulli.ndarray( out.length, [ 0.5 ], 0, 0, out, 1, 0 ); | ||
``` | ||
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The function has the following additional parameters: | ||
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- **op**: starting index for `p`. | ||
- **oo**: starting index for `out`. | ||
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While [`typed array`][mdn-typed-array] views mandate a view offset based on the underlying `buffer`, the offset parameters support indexing semantics based on starting indices. For example, to access every other value in `out` starting from the second value, | ||
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```javascript | ||
var out = [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ]; | ||
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bernoulli.ndarray( 3, [ 0.5 ], 0, 0, out, 2, 1 ); | ||
``` | ||
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#### bernoulli.factory( \[options] ) | ||
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Returns a function for filling strided arrays with pseudorandom numbers drawn from a [Bernoulli][@stdlib/random/base/bernoulli] distribution. | ||
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```javascript | ||
var Float64Array = require( '@stdlib/array/float64' ); | ||
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var random = bernoulli.factory(); | ||
// returns <Function> | ||
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// Create an array: | ||
var out = new Float64Array( 10 ); | ||
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// Fill the array with pseudorandom numbers: | ||
random( out.length, [ 0.5 ], 0, out, 1 ); | ||
``` | ||
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The function accepts the following `options`: | ||
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- **prng**: pseudorandom number generator for generating uniformly distributed pseudorandom numbers on the interval `[0,1)`. If provided, the function **ignores** both the `state` and `seed` options. In order to seed the underlying pseudorandom number generator, one must seed the provided `prng` (assuming the provided `prng` is seedable). | ||
- **seed**: pseudorandom number generator seed. | ||
- **state**: a [`Uint32Array`][@stdlib/array/uint32] containing pseudorandom number generator state. If provided, the function ignores the `seed` option. | ||
- **copy**: `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 an underlying generator has exclusive control over its internal state. Default: `true`. | ||
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To use a custom PRNG as the underlying source of uniformly distributed pseudorandom numbers, set the `prng` option. | ||
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```javascript | ||
var Float64Array = require( '@stdlib/array/float64' ); | ||
var minstd = require( '@stdlib/random/base/minstd' ); | ||
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var opts = { | ||
'prng': minstd.normalized | ||
}; | ||
var random = bernoulli.factory( opts ); | ||
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var out = new Float64Array( 10 ); | ||
random( out.length, [ 0.5 ], 0, out, 1 ); | ||
``` | ||
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To seed the underlying pseudorandom number generator, set the `seed` option. | ||
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```javascript | ||
var Float64Array = require( '@stdlib/array/float64' ); | ||
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var opts = { | ||
'seed': 12345 | ||
}; | ||
var random = bernoulli.factory( opts ); | ||
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var out = new Float64Array( 10 ); | ||
random( out.length, [ 0.5 ], 0, out, 1 ); | ||
``` | ||
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* * * | ||
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#### random.PRNG | ||
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The underlying pseudorandom number generator. | ||
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```javascript | ||
var prng = bernoulli.PRNG; | ||
// returns <Function> | ||
``` | ||
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#### bernoulli.seed | ||
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The value used to seed the underlying pseudorandom number generator. | ||
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```javascript | ||
var seed = bernoulli.seed; | ||
// returns <Uint32Array> | ||
``` | ||
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If the `factory` method is provided a PRNG for uniformly distributed numbers, the associated property value on the returned function is `null`. | ||
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```javascript | ||
var minstd = require( '@stdlib/random/base/minstd-shuffle' ).normalized; | ||
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var random = bernoulli.factory({ | ||
'prng': minstd | ||
}); | ||
// returns <Function> | ||
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var seed = random.seed; | ||
// returns null | ||
``` | ||
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#### bernoulli.seedLength | ||
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Length of underlying pseudorandom number generator seed. | ||
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```javascript | ||
var len = bernoulli.seedLength; | ||
// returns <number> | ||
``` | ||
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If the `factory` method is provided a PRNG for uniformly distributed numbers, the associated property value on the returned function is `null`. | ||
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```javascript | ||
var minstd = require( '@stdlib/random/base/minstd-shuffle' ).normalized; | ||
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var random = bernoulli.factory({ | ||
'prng': minstd | ||
}); | ||
// returns <Function> | ||
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var len = random.seedLength; | ||
// returns null | ||
``` | ||
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#### bernoulli.state | ||
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Writable property for getting and setting the underlying pseudorandom number generator state. | ||
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```javascript | ||
var state = bernoulli.state; | ||
// returns <Uint32Array> | ||
``` | ||
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If the `factory` method is provided a PRNG for uniformly distributed numbers, the associated property value on the returned function is `null`. | ||
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```javascript | ||
var minstd = require( '@stdlib/random/base/minstd-shuffle' ).normalized; | ||
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var random = bernoulli.factory({ | ||
'prng': minstd | ||
}); | ||
// returns <Function> | ||
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var state = random.state; | ||
// returns null | ||
``` | ||
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#### bernoulli.stateLength | ||
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Length of underlying pseudorandom number generator state. | ||
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```javascript | ||
var len = bernoulli.stateLength; | ||
// returns <number> | ||
``` | ||
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If the `factory` method is provided a PRNG for uniformly distributed numbers, the associated property value on the returned function is `null`. | ||
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```javascript | ||
var minstd = require( '@stdlib/random/base/minstd-shuffle' ).normalized; | ||
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var random = bernoulli.factory({ | ||
'prng': minstd | ||
}); | ||
// returns <Function> | ||
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var len = random.stateLength; | ||
// returns null | ||
``` | ||
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#### bernoulli.byteLength | ||
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Size (in bytes) of underlying pseudorandom number generator state. | ||
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```javascript | ||
var sz = bernoulli.byteLength; | ||
// returns <number> | ||
``` | ||
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If the `factory` method is provided a PRNG for uniformly distributed numbers, the associated property value on the returned function is `null`. | ||
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```javascript | ||
var minstd = require( '@stdlib/random/base/minstd-shuffle' ).normalized; | ||
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var random = bernoulli.factory({ | ||
'prng': minstd | ||
}); | ||
// returns <Function> | ||
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var sz = random.byteLength; | ||
// returns null | ||
``` | ||
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</section> | ||
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<!-- /.usage --> | ||
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<section class="notes"> | ||
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* * * | ||
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## Notes | ||
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- If `N <= 0`, both `bernoulli` and `bernoulli.ndarray` leave the output array unchanged. | ||
- Both `bernoulli` and `bernoulli.ndarray` support array-like objects having getter and setter accessors for array element access. | ||
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</section> | ||
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<!-- /.notes --> | ||
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<section class="examples"> | ||
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* * * | ||
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## Examples | ||
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<!-- eslint no-undef: "error" --> | ||
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```javascript | ||
var zeros = require( '@stdlib/array/zeros' ); | ||
var zeroTo = require( '@stdlib/array/zero-to' ); | ||
var logEach = require( '@stdlib/console/log-each' ); | ||
var bernoulli = require( '@stdlib/random/strided/bernoulli' ); | ||
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// Specify a PRNG seed: | ||
var opts = { | ||
'seed': 1234 | ||
}; | ||
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// Create a seeded PRNG: | ||
var rand1 = bernoulli.factory( opts ); | ||
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// Create an array: | ||
var x1 = zeros( 10, 'float64' ); | ||
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// Fill the array with pseudorandom numbers: | ||
rand1( x1.length, [ 0.5 ], 0, x1, 1 ); | ||
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// Create another function for filling strided arrays: | ||
var rand2 = bernoulli.factory( opts ); | ||
// returns <Function> | ||
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// Create a second array: | ||
var x2 = zeros( 10, 'generic' ); | ||
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// Fill the array with the same pseudorandom numbers: | ||
rand2( x2.length, [ 0.5 ], 0, x2, 1 ); | ||
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// Create a list of indices: | ||
var idx = zeroTo( x1.length, 'generic' ); | ||
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// Print the array contents: | ||
logEach( 'x1[%d] = %.2f; x2[%d] = %.2f', idx, x1, idx, x2 ); | ||
``` | ||
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</section> | ||
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<!-- /.examples --> | ||
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<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. --> | ||
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<section class="related"> | ||
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</section> | ||
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<!-- /.related --> | ||
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<!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. --> | ||
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<section class="links"> | ||
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[mdn-typed-array]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray | ||
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[@stdlib/random/base/bernoulli]: https://github.com/stdlib-js/random/tree/main/base/bernoulli | ||
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[@stdlib/array/uint32]: https://github.com/stdlib-js/array-uint32 | ||
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</section> | ||
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<!-- /.links --> |
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