docs: function(vector) {
      var n = this.elements.length;
      var V = vector.elements || vector;
      if (n != V.length) { return false; }
      do {
        if (Math.abs(this.elements[n-1] - V[n-1]) > Sylvester.precision) { return false; }
      } while (--n);
      return true;
    }