# iterDiracComb > Create an iterator which generates a Dirac comb.
A Dirac comb is represented by the following equation
Equation for a Dirac comb.
where `δ` is the Dirac delta function, `T` is the period, and `φ` is the phase offset.
## Usage ```javascript var iterDiracComb = require( '@stdlib/simulate/iter/dirac-comb' ); ``` #### iterDiracComb( \[options] ) Returns an iterator which generates a Dirac comb. ```javascript var it = iterDiracComb(); // returns 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. ```javascript var opts = { 'period': 4 }; var it = iterDiracComb( opts ); // returns 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, ```javascript var opts = { 'period': 4, 'offset': -1 }; var it = iterDiracComb( opts ); // returns 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, ```javascript var opts = { 'period': 4, 'offset': 1 }; var it = iterDiracComb( opts ); // returns 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. ```javascript var opts = { 'iter': 2 }; var it = iterDiracComb( opts ); // returns 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 ```javascript 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 ); } ```
* * * ## See Also - [`@stdlib/simulate/iter/pulse`][@stdlib/simulate/iter/pulse]: create an iterator which generates a pulse waveform.
[@stdlib/simulate/iter/pulse]: https://github.com/stdlib-js/simulate/tree/main/iter/pulse