npm package: @stdlib/simulate-iter-flat-top-pulse
Description: Create an iterator which generates a flat top pulse waveform.
Author: The Stdlib Authors
Latest version: 0.2.3

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# iterFlatTopPulse

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> Create an iterator which generates a flat top pulse waveform.

<!-- Section to include introductory text. Make sure to keep an empty line after the intro `section` element and another before the `/section` close. -->

<section class="intro">

A flat top pulse waveform is represented by the following equation

<!-- <equation class="equation" label="eq:flat_top_pulse_waveform" align="center" raw="f(t; \tau, A, \varphi) = \begin{align*} A\biggl(a_0 &- a_1 \cos\frac{2\pi (t-\varphi)}{\tau-1} + a_2 \cos\frac{2\pi(t-\varphi)}{\tau-1} \\ &- a_3 \cos\frac{2\pi(t-\varphi)}{\tau-1} + a_4 \cos \frac{2\pi (t-\varphi)}{\tau-1} \biggr)\end{align*}" alt="Equation for a flat top pulse waveform."> -->

<div class="equation" align="center" data-raw-text="f(t; T, \tau, A, \varphi) = \begin{align*} A\biggl(a_0 &amp;- a_1 \cos\frac{2\pi (t-\varphi)}{\tau-1} + a_2 \cos\frac{2\pi(t-\varphi)}{\tau-1} \\ &amp;- a_3 \cos\frac{2\pi(t-\varphi)}{\tau-1} + a_4 \cos \frac{2\pi (t-\varphi)}{\tau-1} \biggr)\end{align*}" data-equation="eq:flat_top_pulse_waveform">
    <img src="https://cdn.jsdelivr.net/gh/stdlib-js/stdlib@157025f95b239be39ac0c70158f96243f1be978e/lib/node_modules/@stdlib/simulate/iter/flat-top-pulse/docs/img/equation_flat_top_pulse_waveform.svg" alt="Equation for a flat top pulse waveform.">
    <br>
</div>

<!-- </equation> -->

when `(t-φ)%T < τ` and where `T` is the pulse period, `τ` is the pulse duration, `A` is the amplitude, and `φ` is the phase offset. The waveform is `0` otherwise.

The coefficients are

-   `a_0`: 0.21557895
-   `a_1`: 0.41663158
-   `a_2`: 0.277263158
-   `a_3`: 0.083578947
-   `a_4`: 0.006947368

<!-- TODO: add a figure showing a flat top pulse train -->

</section>

<!-- /.intro -->

<!-- Package usage documentation. -->

<section class="installation">

## Installation

```bash
npm install @stdlib/simulate-iter-flat-top-pulse
```

</section>

<section class="usage">

## Usage

```javascript
var iterFlatTopPulse = require( '@stdlib/simulate-iter-flat-top-pulse' );
```

#### iterFlatTopPulse( \[options] )

Returns an iterator which generates a flat top pulse waveform.

```javascript
var it = iterFlatTopPulse();
// returns <Object>

var v = it.next().value;
// returns <number>

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 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**: pulse period (i.e., the number of iterations before a waveform repeats). Default: `100`.
-   **duration**: pulse duration. Must be greater than `2`. Default: `options.period`.
-   **amplitude**: amplitude. Default: `1.0`.
-   **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 waveform that repeats every `100` iterations. To specify an alternative period, set the `period` option.

```javascript
var opts = {
    'period': 10
};

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

var v = it.next().value;
// returns <number>

v = it.next().value;
// returns <number>

// ...
```

By default, the function returns an iterator which generates a waveform that has a duty cycle of `100%` (i.e., the waveform duration equals the waveform period). To specify an alternative duty cycle, set the `duration` option. For example, to generate a waveform having a period of `10` iterations and a `50%` duty cycle,

```javascript
var opts = {
    'period': 10,
    'duration': 5 // 5/10 = 0.50 => 50%
};

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

var v = it.next().value;
// returns <number>

v = it.next().value;
// returns <number>

v = it.next().value;
// returns <number>

v = it.next().value;
// returns <number>

v = it.next().value;
// returns <number>

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 0.0

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

// ...
```

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': 10,
    'duration': 5,
    'offset': -7
};

var it = iterFlatTopPulse( 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 <number>

v = it.next().value;
// returns <number>

v = it.next().value;
// returns <number>

// ...
```

To translate the waveform to the right,

```javascript
var opts = {
    'period': 10,
    'duration': 5,
    'offset': 2
};

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

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

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

v = it.next().value;
// returns <number>

v = it.next().value;
// returns <number>

v = it.next().value;
// returns <number>

// ...
```

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 = iterFlatTopPulse( opts );
// returns <Object>

var v = it.next().value;
// returns <number>

v = it.next().value;
// returns <number>

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

</section>

<!-- /.usage -->

<!-- Package usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->

<section class="notes">

## Notes

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

</section>

<!-- /.notes -->

<!-- Package usage examples. -->

<section class="examples">

## Examples

<!-- eslint no-undef: "error" -->

```javascript
var iterFlatTopPulse = require( '@stdlib/simulate-iter-flat-top-pulse' );

// Create an iterator:
var opts = {
    'period': 50,
    'duration': 25,
    'amplitude': 10.0,
    'offset': -25,
    'iter': 100
};
var it = iterFlatTopPulse( opts );

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

</section>

<!-- /.examples -->

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<section class="references">

</section>

<!-- /.references -->

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<section class="related">

* * *

## See Also

-   <span class="package-name">[`@stdlib/simulate-iter/pulse`][@stdlib/simulate/iter/pulse]</span><span class="delimiter">: </span><span class="description">create an iterator which generates a pulse waveform.</span>

</section>

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* * *

## Notice

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For more information on the project, filing bug reports and feature requests, and guidance on how to develop [stdlib][stdlib], see the main project [repository][stdlib].

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---

## License

See [LICENSE][stdlib-license].


## Copyright

Copyright &copy; 2016-2026. The Stdlib [Authors][stdlib-authors].

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