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About stdlib...

We believe in a future in which the web is a preferred environment for numerical computation. To help realize this future, we've built stdlib. stdlib is a standard library, with an emphasis on numerical and scientific computation, written in JavaScript (and C) for execution in browsers and in Node.js.

The library is fully decomposable, being architected in such a way that you can swap out and mix and match APIs and functionality to cater to your exact preferences and use cases.

When you use stdlib, you can be absolutely certain that you are using the most thorough, rigorous, well-written, studied, documented, tested, measured, and high-quality code out there.

To join us in bringing numerical computing to the web, get started by checking us out on GitHub, and please consider financially supporting stdlib. We greatly appreciate your continued support!

evalpolyf

NPM version Build Status Coverage Status

Evaluate a polynomial using single-precision floating-point arithmetic.

A polynomial in a variable x can be expressed as

$$c_nx^n + c_{n-1}x^{n-1} + \ldots + c_1x^1 + c_0 = \sum_{i=0}^{n} c_ix^i$$

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

Usage

import evalpolyf from 'https://cdn.jsdelivr.net/gh/stdlib-js/math-base-tools-evalpolyf@esm/index.mjs';

The previous example will load the latest bundled code from the esm branch. Alternatively, you may load a specific version by loading the file from one of the tagged bundles. For example,

import evalpolyf from 'https://cdn.jsdelivr.net/gh/stdlib-js/math-base-tools-evalpolyf@v0.1.0-esm/index.mjs';

You can also import the following named exports from the package:

import { factory } from 'https://cdn.jsdelivr.net/gh/stdlib-js/math-base-tools-evalpolyf@esm/index.mjs';

evalpolyf( c, x )

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

import Float32Array from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-float32@esm/index.mjs';

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 using single-precision floating-point arithmetic.

import Float32Array from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-float32@esm/index.mjs';

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

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 (CSP). If running in or targeting an environment with a CSP, avoid using code generation.

Examples

<!DOCTYPE html>
<html lang="en">
<body>
<script type="module">

import discreteUniform from 'https://cdn.jsdelivr.net/gh/stdlib-js/random-array-discrete-uniform@esm/index.mjs';
import uniform from 'https://cdn.jsdelivr.net/gh/stdlib-js/random-base-uniform@esm/index.mjs';
import evalpolyf from 'https://cdn.jsdelivr.net/gh/stdlib-js/math-base-tools-evalpolyf@esm/index.mjs';

// 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 ) );
}

</script>
</body>
</html>

Notice

This package is part of stdlib, a standard library 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.