function berechne_rund() {

	var durchmesser, laenge;
	var stahl, titan, alu, kupfer, messing;

	durchmesser = document.getElementById("rund_durchmesser").value;
	laenge = document.getElementById("rund_laenge").value;
	stueck = document.getElementById("rund_stueck").value;

	stahl = (durchmesser*durchmesser)*(0.785*0.785)/100*(laenge/1000)*stueck;
	titan = stahl/7.85*4.5;
	alu = stahl/7.85*2.75;
	kupfer = stahl/7.85*8.9;
	messing = stahl/7.85*8.5;

	document.getElementById("rund_g_stahl").value = (Math.round(stahl * 100) / 100);
	document.getElementById("rund_g_titan").value = (Math.round(titan * 100) / 100);
	document.getElementById("rund_g_alu").value = (Math.round(alu * 100) / 100);
	document.getElementById("rund_g_kupfer").value = (Math.round(kupfer * 100) / 100);
	document.getElementById("rund_g_messing").value = (Math.round(messing * 100) / 100);
}

function berechne_rohr1() {

	var ad, ind, laenge, stueck;
	var stahl, titan, alu, kupfer, messing;

	ad = document.getElementById("rohr1_ad").value;
	ind = document.getElementById("rohr1_id").value;
	laenge = document.getElementById("rohr1_laenge").value;
	stueck = document.getElementById("rohr1_stueck").value;

	stahl = ((ad*ad*0.785*0.785/100)-(ind*ind*0.785*0.785/100))/1000*laenge*stueck;
	titan = stahl/7.85*4.5;
	alu = stahl/7.85*2.75;
	kupfer = stahl/7.85*8.9;
	messing = stahl/7.85*8.5;

	document.getElementById("rohr1_g_stahl").value = (Math.round(stahl * 100) / 100);
	document.getElementById("rohr1_g_titan").value = (Math.round(titan * 100) / 100);
	document.getElementById("rohr1_g_alu").value = (Math.round(alu * 100) / 100);
	document.getElementById("rohr1_g_kupfer").value = (Math.round(kupfer * 100) / 100);
	document.getElementById("rohr1_g_messing").value = (Math.round(messing * 100) / 100);
}

function berechne_rohr2() {

	var ad, ind, laenge, stueck;
	var stahl, titan, alu, kupfer, messing;

	ad = document.getElementById("rohr2_ad").value;
	ind = document.getElementById("rohr2_id").value;
	laenge = document.getElementById("rohr2_laenge").value;
	stueck = document.getElementById("rohr2_stueck").value;

	stahl = ((ad*ad*0.785*0.785/100)-((ad-2*ind)*(ad-2*ind)*0.785*0.785/100))/1000*laenge*stueck;
	titan = stahl/7.85*4.5;
	alu = stahl/7.85*2.75;
	kupfer = stahl/7.85*8.9;
	messing = stahl/7.85*8.5;

	document.getElementById("rohr2_g_stahl").value = (Math.round(stahl * 100) / 100);
	document.getElementById("rohr2_g_titan").value = (Math.round(titan * 100) / 100);
	document.getElementById("rohr2_g_alu").value = (Math.round(alu * 100) / 100);
	document.getElementById("rohr2_g_kupfer").value = (Math.round(kupfer * 100) / 100);
	document.getElementById("rohr2_g_messing").value = (Math.round(messing * 100) / 100);
}

function berechne_blech() {

	var dicke, breite, laenge, stueck;
	var faktor8, stahl, titan, alu, kupfer, messing;

	dicke = document.getElementById("blech_dicke").value;
	breite = document.getElementById("blech_breite").value;
	laenge = document.getElementById("blech_laenge").value;
	stueck = document.getElementById("blech_stueck").value;

	faktor8 = (dicke*breite/1000*laenge/1000*8)*stueck;
	stahl = (dicke*breite/1000*laenge/1000*7.85)*stueck;
	titan = stahl/7.85*4.5;
	alu = stahl/7.85*2.75;
	kupfer = stahl/7.85*8.9;
	messing = stahl/7.85*8.5;

	document.getElementById("blech_g_faktor8").value = (Math.round(faktor8 * 100) / 100);
	document.getElementById("blech_g_stahl").value = (Math.round(stahl * 100) / 100);
	document.getElementById("blech_g_titan").value = (Math.round(titan * 100) / 100);
	document.getElementById("blech_g_alu").value = (Math.round(alu * 100) / 100);
	document.getElementById("blech_g_kupfer").value = (Math.round(kupfer * 100) / 100);
	document.getElementById("blech_g_messing").value = (Math.round(messing * 100) / 100);
}

function berechne_alles() {
	berechne_rund();
	berechne_rohr1();
	berechne_rohr2();
	berechne_blech();
}

function Gewichtsrechner() {
var breite, hoehe, links, oben;
  breite = screen.availWidth;
  hoehe = screen.availHeight;
  
  links = (breite-900)/2;
  oben = (hoehe-500)/2;
  
  var MeinFenster = window.open("gewicht.html", "Gewichtsrechner", "width=900,height=500,left=" + links + ",top=" + oben + ",scrollbars=yes,resizable=yes");
  MeinFenster.focus();
}