Method multiply

docs/app/js/sanddance-app.js:69189–69192

(...vectors)

        return this.check();
    }
    multiply(...vectors) {
        for (const vector of vectors)for(let i = 0; i < this.ELEMENTS; ++i)this[i] *= vector[i];
        return this.check();
    }
    divide(...vectors) {
        for (const vector of vectors)for(let i = 0; i < this.ELEMENTS; ++i)this[i] /= vector[i];
        return this.check();