import { Real } from "./real" ; const { sqrt } = Math ; /**
 *  https public export type Vector = Array < number > ; public export namespace Vector { export function isVector ( value ) { return Array . isArray ( value ) && value . every ( ( n ) => typeof n === "number" ) ; } export function clone ( v ) { return v . slice ( 0 ) ; } export function equals ( v , u , e ) { return v . length === u . length && v . every ( ( n , i ) => Real . equals ( n , u [ i ] , e ) ) ; } export function size ( v ) { return v . length ; } export function add ( v , u ) { return v . map ( ( n , i ) => n + u ?. [ i ] ) ; } export function subtract ( v , u ) { return v . map ( ( n , i ) => n - u ?. [ i ] ) ; } export function multiply ( v , s ) { return v . map ( ( n ) => n * s ) ; } export function divide ( v , d ) { return v . map ( ( n ) => n / d ) ; } /**
     * Compute the dot product of two non-empty, equal length vectors.
     *
     *  https export function dot ( v , u ) { return v . reduce ( ( s , n , i ) => s + n * u ?. [ i ] , 0 ) ; } /**
     * Compute the cross product of two 3-dimensional vectors.
     *
     *  https export function cross ( v , u ) { const [ vx , vy , vz ] = v ; const [ ux , uy , uz ] = u ; return [ vy * uz - vz * uy , vz * ux - vx * uz , vx * uy - vy * ux ] ; } /**
     * Compute the norm of a vector.
     *
     *  https export function norm ( v ) { return sqrt ( v . reduce ( ( s , n ) => s + n ** 2 , 0 ) ) ; } /**
     * Compute a unit vector corresponding to a vector.
     *
     *  https export function normalize ( v ) { return divide ( v , norm ( v ) ) ; } }