Package Exports

math-evalpoly

This package does not declare an exports field, so the exports above have been automatically detected and optimized by JSPM instead. If any package subpath is missing, it is recommended to post an issue to the original package (math-evalpoly) to support the "exports" field. If that is not possible, create a JSPM override to customize the exports field for this package.

Readme

evalpoly

$NPM version$ $Build Status$ $Coverage Status$ $Dependencies$

Evaluates a polynomial.

Installation

$ npm install math-evalpoly

Usage

var evalpoly = require( 'math-evalpoly' );

evalpoly( c, x )

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

var v = evalpoly( [3,2,1], 10 );
// returns 123 => 3*10^0 + 2*10^1 + 1*10^2

The coefficients should be ordered in ascending degree. For example, for a polynomial

$Polynomial expression.$

the coefficients would be

[c_0, c_1, ..., c_(n-1), c_n]

matching the summation notation.

evalpoly.factory( c )

Uses code generation to in-line coefficients and return a reusable function for evaluating a polynomial.

var poly = evalpoly.factory( [3,2,1] );

var v = poly( 10 );
// returns 123 => 3*10^0 + 2*10^1 + 1*10^2

v = poly( 5 );
// returns 38 => 3*5^0 + 2*5^1 + 1*5^2

Note: For hot code paths in which coefficients are invariant, the generated function will be more performant than the main export.

Examples

var round = require( 'math-round' );
var evalpoly = require( 'math-evalpoly' );

var coef;
var sign;
var poly;
var v;
var i;

// Create an array of random coefficients...
coef = new Float64Array( 10 );
for ( i = 0; i < coef.length; i++ ) {
    if ( Math.random() < 0.5 ) {
        sign = -1;
    } else {
        sign = 1;
    }
    coef[ i ] = sign * round( Math.random()*100 );
}

// Evaluate the polynomial at random values...
for ( i = 0; i < 100; i++ ) {
    v = Math.random() * 100;
    console.log( 'f(%d) = %d', v, evalpoly( coef, v ) );
}

// Generate an `evalpoly` function...
poly = evalpoly.factory( coef );
for ( i = 0; i < 100; i++ ) {
    v = Math.random()*100 - 50;
    console.log( 'f(%d) = %d', v, poly( v ) );
}

To run the example code from the top-level application directory,

$ node ./examples/index.js

Tests

Unit

This repository uses tape for unit tests. To run the tests, execute the following command in the top-level application directory:

$ make test

All new feature development should have corresponding unit tests to validate correct functionality.

Test Coverage

This repository uses Istanbul as its code coverage tool. To generate a test coverage report, execute the following command in the top-level application directory:

$ make test-cov

Istanbul creates a ./reports/coverage directory. To access an HTML version of the report,

$ make view-cov

Browser Support

This repository uses Testling for browser testing. To run the tests in a (headless) local web browser, execute the following command in the top-level application directory:

$ make test-browsers

To view the tests in a local web browser,

$ make view-browser-tests

License

MIT license.

math-evalpoly