orep-js/sunpy/core/vector.js

const DIM_NAMES = ["xr", "yg", "zb", "wa"];
const ARRAY_TYPES = [
    Int8Array, Int16Array, Int32Array,
    Uint8Array, Uint16Array, Uint32Array,
    Float32Array, Float64Array,
    BigInt64Array, BigUint64Array // Note: These requires values to be of type BigInt
];

export class Vector {
    constructor(...values) {
        this.type = Float32Array;

        for (const value of values) {
            if (ARRAY_TYPES.includes(value)) {
                this.type = value;
                break;
            }
        }

        this.values = new this.type(values.filter(v => !ARRAY_TYPES.includes(v)));

        const defineMacro = (index, key) => {
            Object.defineProperty(this, key, {
                get() { return this.values[index] },
                set(value) { this.values[index] = value }
            });
        };

        for (const i in this.values) {
            defineMacro(i, i);

            if (i >= DIM_NAMES.length)
                continue;
            
            for (const names of DIM_NAMES[i]) {
                for (const char of names) {
                    defineMacro(i, char);
                }
            }
        }
    }

    clone() {
        return new Vector(this.type, ...this.values);
    }

    static _requireSameVector(vecA, vecB) {
        if (!(vecA instanceof Vector))
            throw new TypeError("vecA has to be instance of `Vector`");
        
        if (!(vecB instanceof Vector))
            throw new TypeError("vecB has to be instance of `Vector`");

        if (vecA.values.length !== vecB.values.length)
            throw new TypeError("Vectors are of different lengths");
        
        if (vecA.type !== vecB.type)
            console.warn("Vectors are not of same array type.. be careful!");
    }

    _modifyComponents(vec, func) {
        if (vec instanceof Vector) {
            Vector._requireSameVector(this, vec);
            
            for (const i in vec.values) {
                this[i] = func(this[i], vec[i]);
            }

            return this;
        }

        for (const i in this.values) {
            this[i] = func(this[i], vec); // vec is number here
        }

        return this;
    }

    // Basic operations
    add = (vec) => this._modifyComponents(vec, (a, b) => a + b);
    subtract = (vec) => this._modifyComponents(vec, (a, b) => a - b);
    multiply = (vec) => this._modifyComponents(vec, (a, b) => a * b);
    divide = (vec) => this._modifyComponents(vec, (a, b) => a / b);

    // Basic algebra
    length() {
        return Math.sqrt( this.values.map(v => v * v).reduce((a, b) => a + b, 0) );
    }

    static normalize(vec) {
        return vec.clone().divide(vec.length());
    }

    static distance(vecA, vecB) {
        Vector._requireSameVector(vecA, vecB);
        return Math.sqrt( vecA.values.map((v, i) => v - vecB[i]).map(v => v * v).reduce((a, b) => a + b, 0) );
    }

    static dot(vecA, vecB) {
        Vector._requireSameVector(vecA, vecB);
        return vecA.values.map((v, i) => v * vecB[i]).reduce((a, b) => a + b, 0);
    }

    static cross(vecA, vecB) {
        Vector._requireSameVector(vecA, vecB);

        if (vecA.values.length !== 3)
            throw TypeError(`Vector3 required, got Vector${vecA.values.length}`);
        
        return new Vector(vecA.type,
            vecA.y * vecB.z - vecA.z * vecB.y,
            vecA.z * vecB.x - vecA.x * vecB.z,
            vecA.x * vecB.y - vecA.y * vecB.x
            );
    }
}