npm package: @stdlib/math-base-special-lucasf
Description: Compute the nth Lucas number as a single-precision floating-point number.
Author: The Stdlib Authors
Latest version: 0.1.1

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# lucasf

[![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url] <!-- [![dependencies][dependencies-image]][dependencies-url] -->

> Compute the nth [Lucas number][lucas-number] as a single-precision floating-point number.

<section class="intro">

The [Lucas numbers][lucas-number] are the integer sequence

<!-- <equation class="equation" label="eq:lucas_sequence" align="center" raw="2, 1, 3, 4, 7, 11, 18, 29, 47, 76, 123, 199, 322, \ldots" alt="Lucas sequence"> -->

<!-- </equation> -->

The sequence is defined by the recurrence relation

<!-- <equation class="equation" label="eq:lucas_recurrence_relation" align="center" raw="L_n = \begin{cases}2 & \textrm{if}\ n = 0\\1 & \textrm{if}\ n = 1\\L_{n-1} + L_{n-2} & \textrm{if}\ n > 1\end{cases}" alt="Lucas sequence recurrence relation"> -->

<!-- </equation> -->

</section>

<!-- /.intro -->

<section class="installation">

## Installation

```bash
npm install @stdlib/math-base-special-lucasf
```

</section>

<section class="usage">

## Usage

```javascript
var lucasf = require( '@stdlib/math-base-special-lucasf' );
```

#### lucasf( n )

Computes the nth [Lucas number][lucas-number] as a single-precision floating-point number.

```javascript
var v = lucasf( 0 );
// returns 2

v = lucasf( 1 );
// returns 1

v = lucasf( 2 );
// returns 3

v = lucasf( 3 );
// returns 4

v = lucasf( 34 );
// returns 12752043
```

If `n > 34`, the function returns `NaN`, as larger [Lucas numbers][lucas-number] cannot be safely represented in [single-precision floating-point format][ieee754].

```javascript
var v = lucasf( 35 );
// returns NaN
```

If not provided a nonnegative integer value, the function returns `NaN`.

```javascript
var v = lucasf( 3.14 );
// returns NaN

v = lucasf( -1 );
// returns NaN
```

If provided `NaN`, the function returns `NaN`.

```javascript
var v = lucasf( NaN );
// returns NaN
```

</section>

<!-- /.usage -->

<section class="notes">

</section>

<!-- /.notes -->

<section class="examples">

## Examples

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

```javascript
var discreteUniform = require( '@stdlib/random-array-discrete-uniform' );
var logEachMap = require( '@stdlib/console-log-each-map' );
var lucasf = require( '@stdlib/math-base-special-lucasf' );

var x = discreteUniform( 10, 0, 34, {
    'dtype': 'int32'
});

logEachMap( 'lucasf(%d) = %0.1f', x, lucasf );
```

</section>

<!-- /.examples -->

<!-- C interface documentation. -->

* * *

<section class="c">

## C APIs

<!-- 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">

</section>

<!-- /.intro -->

<!-- C usage documentation. -->

<section class="usage">

### Usage

```c
#include "stdlib/math/base/special/lucasf.h"
```

#### stdlib_base_lucasf( n )

Computes the nth [Lucas number][lucas-number] as a single-precision floating-point number.

```c
float out = stdlib_base_lucasf( 0.0f );
// returns 2.0f

out = stdlib_base_lucasf( 1.0f );
// returns 1.0f
```

The function accepts the following arguments:

-   **n**: `[in] float` input value.

```c
float stdlib_base_lucasf( const float n );
```

</section>

<!-- /.usage -->

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

<section class="notes">

</section>

<!-- /.notes -->

<!-- C API usage examples. -->

<section class="examples">

### Examples

```c
#include "stdlib/math/base/special/lucasf.h"
#include <stdio.h>

int main( void ) {
    float i;
    float v;

    for ( i = 0.0f; i < 35.0f; i++ ) {
        v = stdlib_base_lucasf( i );
        printf( "lucasf(%f) = %f\n", i, v );
    }
}
```

</section>

<!-- /.examples -->

</section>

<!-- /.c -->

<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. -->

<section class="related">

</section>

<!-- /.related -->

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<section class="main-repo" >

* * *

## Notice

This package is part of [stdlib][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][stdlib], see the main project [repository][stdlib].

#### Community

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---

## License

See [LICENSE][stdlib-license].


## Copyright

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

</section>

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[umd]: https://github.com/umdjs/umd
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[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/math-base-special-lucasf/main/LICENSE

[lucas-number]: https://en.wikipedia.org/wiki/Lucas_number

[ieee754]: https://en.wikipedia.org/wiki/IEEE_754-1985

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</section>

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