nvas("interpolation_canvas");
}

function reset_all_for_both() {
	points_for_both = [[37, 195], [66, 345], [197, 473], [420, 465], [560, 315], [587, 172]];
	both_i = 0;
	draw_canvas("both_canvas");
}

function undo_last_for_both() {
	points_for_both.splice(-1,1);
	draw_canvas("both_canvas");
}

// facts
function show(n){
	document.getElementById("hidden_" + n).style.display = "inline";
}

function is_shown(n){
	return document.getElementById("hidden_" + n).style.display == "inline";
}

function show_approxi