ementById("shown_" + n).style.display = "none";
	document.getElementById("hidden_" + n).style.display = "inline";
	console.log(n);

}

function undo_last_point() {
	if(points.length > 1)
		points.pop();
}

function reset_all_points() {
	points = [[-4., 1.], [1., 4.], [4., -1.]];
}
reset_all_points();

	</script>
</head>
<body>
	<center>


	<table style="width: 505pt;" class="footer">
	<tr>
	<td class="footer" style="text-align: left;"><a href="atan31.html">&larr; </a></td>
	<td class="footer" style="text-al