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iterDiracComb

Create an iterator which generates a Dirac comb.

A Dirac comb is represented by the following equation

$$f(t; T, \varphi) = \delta((t-\varphi) \bmod T)$$

where δ is the Dirac delta function, T is the period, and φ is the phase offset.

Installation

npm install @stdlib/simulate-iter-dirac-comb

Alternatively,

• To load the package in a website via a script tag without installation and bundlers, use the ES Module available on the esm branch (see README).
• If you are using Deno, visit the deno 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).

The branches.md file summarizes the available branches and displays a diagram illustrating their relationships.

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.

Usage

var iterDiracComb = require( '@stdlib/simulate-iter-dirac-comb' );

iterDiracComb( [options] )

Returns an iterator which generates a Dirac comb.

var it = iterDiracComb();
// returns <Object>

var v = it.next().value;
// returns Infinity

v = it.next().value;
// returns 0.0

v = it.next().value;
// returns 0.0

// ...

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 a done property having a boolean 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.

The function supports the following options:

• period: period (i.e., the number of iterations before a waveform repeats). Default: 10.
• offset: phase offset (in units of iterations; zero-based). A negative offset translates a waveform to the left. A positive offset translates a waveform to the right. Default: 0.
• iter: number of iterations. Default: 1e308.

By default, the function returns an iterator which generates a Dirac delta function that repeats every 10 iterations. To specify an alternative period, set the period option.

var opts = {
    'period': 4
};

var it = iterDiracComb( opts );
// returns <Object>

var v = it.next().value;
// returns Infinity

v = it.next().value;
// returns 0.0

v = it.next().value;
// returns 0.0

v = it.next().value;
// returns 0.0

v = it.next().value;
// returns Infinity

// ...

To adjust at what point the iterator begins in the waveform cycle, set the phase offset option. For example, to translate the waveform to the left,

var opts = {
    'period': 4,
    'offset': -1
};

var it = iterDiracComb( opts );
// returns <Object>

var v = it.next().value;
// returns 0.0

v = it.next().value;
// returns 0.0

v = it.next().value;
// returns 0.0

v = it.next().value;
// returns Infinity

v = it.next().value;
// returns 0.0

// ...

To translate the waveform to the right,

var opts = {
    'period': 4,
    'offset': 1
};

var it = iterDiracComb( opts );
// returns <Object>

var v = it.next().value;
// returns 0.0

v = it.next().value;
// returns Infinity

v = it.next().value;
// returns 0.0

v = it.next().value;
// returns 0.0

v = it.next().value;
// returns 0.0

// ...

By default, the function returns an infinite iterator (i.e., an iterator which never ends). To limit the number of iterations, set the iter option.

var opts = {
    'iter': 2
};
var it = iterDiracComb( opts );
// returns <Object>

var v = it.next().value;
// returns Infinity

v = it.next().value;
// returns 0.0

var bool = it.next().done;
// returns true

Notes

• If an environment supports Symbol.iterator, the returned iterator is iterable.

Examples

var iterDiracComb = require( '@stdlib/simulate-iter-dirac-comb' );

// Create an iterator:
var opts = {
    'period': 10,
    'offset': -5,
    'iter': 100
};
var it = iterDiracComb( opts );

// Perform manual iteration...
var v;
while ( true ) {
    v = it.next();
    if ( v.done ) {
        break;
    }
    console.log( v.value );
}

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See Also

• @stdlib/simulate-iter/pulse: create an iterator which generates a pulse waveform.

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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

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License

See LICENSE.

Copyright

Copyright © 2016-2024. The Stdlib Authors.