// Calculate
let a = new Vector(10, 20)  
let b = new Vector(30, 40)
let c = a.add(b).rotate(Vector.rad(30)) 

// Use
console.log('x: ' + c.x)    
console.log('y: ' + c.y)
console.log('length: ' + c.norm())
console.log('angle in degrees: ' + Vector.deg(c.angle()))

Description

2D-vector operations: addition, subtraction, normalization, rotation etc.

The vectors are immutable and therefore safe to use. Every operation returns new instance.

Installation

Install with npm

npm i @minogin/vector

Add the following line to your javascript code

import Vector from '@minogin/vector'

Documentation

Constructors

Vector(x, y)

• x, y {Number} - initial vector coordinates

let v = new Vector(10, -20)

Vector(v)

• v {Vector} - vector to clone

let a = new Vector(10, 20)
let b = new Vector(a)       // b = { 10; 20 }

Operators and functions

add(v)

• v {Vector} - vector to add
• returns: Vector

Returns sum of current vector and v

let a = new Vector(10, 20)
let b = a.add(new Vector(30, 40))   // b = { 40; 60 }

sub(v)

• v {Vector} - vector to subtract
• returns: Vector

Returns difference of current vector and v

let a = new Vector(30, 40)
let b = a.sub(new Vector(10, 30))   // b = { 20; 10 }

neg(v)

• returns: Vector

Returns vector negative (inverse) to current

let a = new Vector(10, -20)
let b = a.neg()     // a = {-10; 20}

mul(v)

• v {Vector} - vector to multiply by
• returns: Vector

Returns dot product of current vector and another

let a = new Vector(2, 3)
let p = a.mul(new Vector(4, 5))     // p = 2*4 + 3*5 = 23  

norm()

• returns: Vector

Returns norm (length) of current vector

let n = new Vector(3, 4).norm()     // n = 5  

unit()

• returns: Vector

Returns unit vector (length = 1) directed same as current

let u = new Vector(5, -5).unit()     // u = { √2/2; -√2/2 }

rotate(angle)

• angle {Number} - angle in radians
• returns: Vector

Returns current vector rotated by angle (radians)

let b = new Vector(1, 0).rotate(Math.PI / 6)     // b = { √3/2; 1/2 }

See also: Vector.rad(degrees)

angle()

• returns: Number

Computes current vector's angle (to x axis) in radians

let phi = new Vector(Math.sqrt(3)/2, 1/2).angle()     // phi = Math.PI / 6

See also: Vector.deg(radians)

equals(v[, precision])

• v {Vector} - vector to compare to
• precision {Number} - precision of comparison, defaults to Number.EPSILON
• returns: Boolean

Checks whether this vector is equal (with given precision) to another.

Be careful! Number.EPSILON may be too small for most floating point operations.

let v = new Vector(Math.sqrt(3)/2, 1/2).rotate(-Math.PI / 6) 
if (v.equals(new Vector(1, 0))) { /*...*/ }     // May be false!
if (v.equals(new Vector(1, 0), 1e-10)) { /*...*/ }     // It is true

clone()

• returns: Vector

v.clone() is identical to new Vector(v)

Utilities

Vector.rad(degrees)

• degrees {Number} - angle in degrees
• returns: Number

Converts degrees to radians.

new Vector(10, 20).rotate(Vector.rad(30)) 

Vector.deg(radians)

• radians {Number} - angle in radians
• returns: Number

Converts radians to degrees.

let v = new Vector(Math.sqrt(3)/2, 1/2)
console.log('Vector is rotated by ' + Math.deg(v.angle()) + ' degrees')

License

ISC