⁴The turtle length relative to the window size \(\ell \) and head half-angle \(\alpha \) are respectively the Lisp float values of the symbolic-mode global variables logoturtle!-rel!-len!*and logoturtle!-angle!*. These values are used dynamically and in principle you could change them after LogoTurtle has loaded, but currently there is no algebraic-mode facility to do this.