npm package: @stdlib/math-base-tools-evalpolyf
Description: Evaluate a polynomial using single-precision floating-point arithmetic.
Author: The Stdlib Authors
Latest version: 0.1.2

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# evalpolyf

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

> Evaluate a [polynomial][polynomial] using single-precision floating-point arithmetic.

<section class="intro">

A [polynomial][polynomial] in a variable `x` can be expressed as

<!-- <equation class="equation" label="eq:polynomial" align="center" raw="c_nx^n + c_{n-1}x^{n-1} + \ldots + c_1x^1 + c_0 = \sum_{i=0}^{n} c_ix^i" alt="Polynomial expression."> -->

<div class="equation" align="center" data-raw-text="c_nx^n + c_{n-1}x^{n-1} + \ldots + c_1x^1 + c_0 = \sum_{i=0}^{n} c_ix^i" data-equation="eq:polynomial">
    <img src="https://cdn.jsdelivr.net/gh/stdlib-js/stdlib@7e0a95722efd9c771b129597380c63dc6715508b/lib/node_modules/@stdlib/math/base/tools/evalpoly/docs/img/equation_polynomial.svg" alt="Polynomial expression.">
    <br>
</div>

<!-- </equation> -->

where `c_n, c_{n-1}, ..., c_0` are constants.

</section>

<!-- /.intro -->

<section class="installation">

## Installation

```bash
npm install @stdlib/math-base-tools-evalpolyf
```

</section>

<section class="usage">

## Usage

```javascript
var evalpolyf = require( '@stdlib/math-base-tools-evalpolyf' );
```

#### evalpolyf( c, x )

Evaluates a [polynomial][polynomial] having coefficients `c` and degree `n` at a value `x`, where `n = c.length-1`.

```javascript
var Float32Array = require( '@stdlib/array-float32' );

var v = evalpolyf( new Float32Array( [ 3.0, 2.0, 1.0 ] ), 10 ); // => 3*10^0 + 2*10^1 + 1*10^2
// returns 123.0
```

The coefficients should be ordered in **ascending** degree, thus matching summation notation.

#### evalpolyf.factory( c )

Uses code generation to in-line coefficients and return a function for evaluating a [polynomial][polynomial] using single-precision floating-point arithmetic.

```javascript
var Float32Array = require( '@stdlib/array-float32' );

var polyval = evalpolyf.factory( new Float32Array( [ 3.0, 2.0, 1.0 ] ) );

var v = polyval( 10.0 ); // => 3*10^0 + 2*10^1 + 1*10^2
// returns 123.0

v = polyval( 5.0 ); // => 3*5^0 + 2*5^1 + 1*5^2
// returns 38.0
```

</section>

<!-- /.usage -->

<section class="notes">

## Notes

-   For hot code paths in which coefficients are invariant, a compiled function will be more performant than `evalpolyf()`.
-   While code generation can boost performance, its use may be problematic in browser contexts enforcing a strict [content security policy][mdn-csp] (CSP). If running in or targeting an environment with a CSP, avoid using code generation.

</section>

<!-- /.notes -->

<section class="examples">

## Examples

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

```javascript
var discreteUniform = require( '@stdlib/random-array-discrete-uniform' );
var uniform = require( '@stdlib/random-base-uniform' );
var evalpolyf = require( '@stdlib/math-base-tools-evalpolyf' );

// Create an array of random coefficients:
var coef = discreteUniform( 10, -100, 100, {
    'dtype': 'float32'
});

// Evaluate the polynomial at random values:
var v;
var i;
for ( i = 0; i < 100; i++ ) {
    v = uniform( 0.0, 100.0 );
    console.log( 'f(%d) = %d', v, evalpolyf( coef, v ) );
}

// Generate an `evalpolyf` function:
var polyval = evalpolyf.factory( coef );
for ( i = 0; i < 100; i++ ) {
    v = uniform( -50.0, 50.0 );
    console.log( 'f(%d) = %d', v, polyval( v ) );
}
```

</section>

<!-- /.examples -->

<!-- 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].

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[polynomial]: https://en.wikipedia.org/wiki/Polynomial

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