V8/usr/src/cmd/ideal/lib/arrow

.IS
arrow {
	var tl, hd, head, perp, headang;
	conn tl to hd;
	perp = head*(tl-hd)/abs(tl-hd);
	conn hd + cis(headang)*perp to hd to hd + cis(-headang)*perp;
	head ~ 0.1;
        headang ~ 25;
}
.IE