Interval

Class to work with intervals of real numbers.

Version

0.1.1

Install

npm install math.interval

Usage

var Interval = require('math.interval')

var interval = new Interval('(1, 5)')

interval.isEmpty() // false
interval.contains(4) // true
interval.contains('[2, 3)') // true
interval.union('[8, 9)') // [new Interval('(1, 5)'), new Interval('[8, 9)')]
interval.union('(4, 6])') // [new Interval('(1, 6]')]

var isolatedInterval = new Interval('{3}') // equivalent to [3, 3]
isolatedInterval.isEmpty() // false
interval.contains(isolatedInterval) // true

API

Interval

constructor(interval)

Constructor creates an instance of Interval class. it throws an exception if interval is not IntervalCastable

Interval#isEmpty()

It returns true or false if interval is empty or not.

Example:

var Interval = require('math.interval')

var new Interval('[2, 4)')

interval.isEmpty() // returns false

Interval#contains(interval)

It returns true or false if instance contains interval passed by parameter. contains throws an exception if interval is not IntervalCastable

Example:

var Interval = require('math.interval')

var interval = new Interval('[1, 3)')

interval.contains('(1, 2)') // returns true
interval.contains(new Interval('[5, 6]')) // returns false

Interval#union(...intervals)

It returns an array of minimum disjoint intervals that represents the union of instance of interval with intervals passed by parameter.

var Interval = require('math.interval')

var interval = new Interval('[1, 3)')

interval.union('(2, 4)', '{5}', '(5, 6)')
// returns [new Interval('[1, 4)'), new Interval('[5, 6)')]

Interval.union(...intervals)

Interval also has static method that calculates the union of intervals in the same way as union method.

var Interval = require('math.interval')

Interval.union('[1, 3)', '(2, 4)', '{5}', '(5, 6)')
// returns [new Interval('[1, 4)'), new Interval('[5, 6)')]

Interval#toString()

It returns an string with a expression representation of interval

var Interval = require('math.interval')

var a = new Interval('(2, 5]')
var b = new Interval('(5, 2]') // empty
var c = new Interval('[2, 2]') // singleton interval

a.toString() // '(2, 5]'
b.toString() // '{}'
c.toString() // '{2}'

IntervalCastable

A value is IntervalCastable if it is one of this list of types:

• instance of Interval.
• string that parses with interval ('[2, 5]', '[0, 5)', '{3}', '(-2, 1)', etc).
• data structure defined in math.interval-utils package.

Exported functions

rawInterval(interval)

It converts Interval instance to interval data structure defined in math.interval-utils package. It is posible to import this function thus:

var rawInterval = require('math.interval/src/raw-interval.js')

cast(interval)

It converts IntervalCastable value to interval data structure defined in math.interval-utils package. It is posible to import this function thus:

var rawInterval = require('math.interval/src/cast.js')

LICENSE

MIT