function Vector(x, y) {
    if (x === undefined)
        x = 0;
    if (y === undefined)
        y = 0;
    this.x = x;
    this.y = y;

    this.add = function(x, y) {
        if (y === undefined)
            y = x;
        this.x += x;
        this.y += y;
        return this;
    };
    this.addVector = function(other) {
        this.x += other.x;
        this.y += other.y;
        return this;
    };
    this.subtract = function(x, y) {
        if (y === undefined)
            y = x;
        this.x -= x;
        this.y -= y;
        return this;
    };
    this.subtractVector = function(other) {
        this.x -= other.x;
        this.y -= other.y;
        return this;
    };
    this.multiply = function(x, y) {
        if (y === undefined)
            y = x;
        this.x *= x;
        this.y *= y;
        return this;
    };
    this.multiplyVector = function(other) {
        this.x *= other.x;
        this.y *= other.y;
        return this;
    };
    this.divide = function(x, y) {
        if (y === undefined)
            y = x;
        this.x /= x;
        this.y /= y;
        return this;
    };
    this.divideVector = function(other) {
        this.x /= other.x;
        this.y /= other.y;
        return this;
    };
    this.magnitude = function() {
        return Math.sqrt(this.x * this.x + this.y * this.y);
    };
    this.direction = function() {
        return Math.atan(this.y / this.x);
    };
    this.distance = function(other) {
        return Math.sqrt(Math.pow(this.x - other.x, 2) + Math.pow(this.y - other.y, 2));
    };
    this.crossProduct = function(other) {
        return this.x * other.y - this.y * other.x;
    };
    this.normalize = function() {
        if (this.x == 0 && this.y == 0) {}
        else if (this.x == 0)
            this.divide(1, this.magnitude());
        else if (this.y == 0)
            this.divide(this.magnitude(), 1);
        else
            this.divide(this.magnitude());
        return this;
    };

    this.toString = function() {
        return this.x + "," + this.y;
    };
    this.clone = function() {
        return new Vector(this.x, this.y);
    };
    this.equals = function(other) {
        return other.x == this.x && other.y == this.y;
    };
}