function show_web_graph() {
	var web_graph = document.getElementById("web_graph");
	var software_graph = document.getElementById("software_graph");
	var hardware_graph = document.getElementById("hardware_graph");
	
	document.getElementById("web_graph_link").setAttribute('class', 'selected');
	document.getElementById("software_graph_link").setAttribute('class', '');
	document.getElementById("hardware_graph_link").setAttribute('class', '');
	
	web_graph.style.visibility = "visible";
	software_graph.style.visibility = "hidden";
	hardware_graph.style.visibility = "hidden";
}

function show_software_graph() {
	var web_graph = document.getElementById("web_graph");
	var software_graph = document.getElementById("software_graph");
	var hardware_graph = document.getElementById("hardware_graph");
	
	document.getElementById("web_graph_link").setAttribute('class', '');
	document.getElementById("software_graph_link").setAttribute('class', 'selected');
	document.getElementById("hardware_graph_link").setAttribute('class', '');
	
	web_graph.style.visibility = "hidden";
	software_graph.style.visibility = "visible";
	hardware_graph.style.visibility = "hidden";
}

function show_hardware_graph() {
	var web_graph = document.getElementById("web_graph");
	var software_graph = document.getElementById("software_graph");
	var hardware_graph = document.getElementById("hardware_graph");
	
	document.getElementById("web_graph_link").setAttribute('class', '');
	document.getElementById("software_graph_link").setAttribute('class', '');
	document.getElementById("hardware_graph_link").setAttribute('class', 'selected');
	
	web_graph.style.visibility = "hidden";
	software_graph.style.visibility = "hidden";
	hardware_graph.style.visibility = "visible";
}