function displayUnit(id){
if(id == 'temperature'){
document.getElementById('surface').style.display = "none";
document.getElementById('longueur').style.display = "none";
document.getElementById('pression').style.display = "none";
document.getElementById('debit').style.display = "none";
document.getElementById('volume').style.display = "none";
}else if(id == 'surface'){
document.getElementById('longueur').style.display = "none";
document.getElementById('temperature').style.display = "none";
document.getElementById('pression').style.display = "none";
document.getElementById('debit').style.display = "none";
document.getElementById('volume').style.display = "none";
}else if(id == 'longueur'){
document.getElementById('surface').style.display = "none";
document.getElementById('temperature').style.display = "none";
document.getElementById('pression').style.display = "none";
document.getElementById('debit').style.display = "none";
document.getElementById('volume').style.display = "none";
}else if(id == 'pression'){
document.getElementById('surface').style.display = "none";
document.getElementById('temperature').style.display = "none";
document.getElementById('longueur').style.display = "none";
document.getElementById('debit').style.display = "none";
document.getElementById('volume').style.display = "none";
}else if(id == 'debit'){
document.getElementById('surface').style.display = "none";
document.getElementById('temperature').style.display = "none";
document.getElementById('longueur').style.display = "none";
document.getElementById('pression').style.display = "none";
document.getElementById('volume').style.display = "none";
}else if(id == 'volume'){
document.getElementById('surface').style.display = "none";
document.getElementById('temperature').style.display = "none";
document.getElementById('longueur').style.display = "none";
document.getElementById('pression').style.display = "none";
document.getElementById('debit').style.display = "none";
}
document.getElementById(id).style.display = "block";
}
function calcul(p){
var value = document.getElementById(p+'_value').value ;
var unitFrom = unitetab[document.getElementById(p+'_unitFrom').value] ;
var unitTo = unitetab[document.getElementById(p+'_unitTo').value] ;
var result = unitFrom.convert(value, unitTo);
document.getElementById(p+'_result').value = roundFloat(result);
}
function writeSelects(){
var elem = new Array();
elem[0] = document.getElementById('l_unitFrom') ;
elem[1] = document.getElementById('l_unitTo') ;
elem[2] = document.getElementById('s_unitFrom') ;
elem[3] = document.getElementById('s_unitTo') ;
elem[4] = document.getElementById('t_unitFrom') ;
elem[5] = document.getElementById('t_unitTo') ;
elem[6] = document.getElementById('p_unitFrom') ;
elem[7] = document.getElementById('p_unitTo') ;
elem[8] = document.getElementById('d_unitFrom') ;
elem[9] = document.getElementById('d_unitTo') ;
elem[10] = document.getElementById('v_unitFrom') ;
elem[11] = document.getElementById('v_unitTo') ;

var opt = '';
for (var i=0; i < unitetab.length; i++) {
opt1 = new Option(unitetab[i].symbole + ' (' + unitetab[i].nom +')', i); 
opt2 = new Option(unitetab[i].symbole + ' (' + unitetab[i].nom +')', i); 
if (unitetab[i].type == 'Longueur'){
elem[0].options[elem[0].length] = opt1 ;
elem[1].options[elem[1].length] = opt2 ;
}else if (unitetab[i].type == 'Surface'){
elem[2].options[elem[2].length] = opt1 ;
elem[3].options[elem[3].length] = opt2 ;
}else if (unitetab[i].type == 'Température'){
elem[4].options[elem[4].length] = opt1 ;
elem[5].options[elem[5].length] = opt2 ;
}else if (unitetab[i].type == 'Pression'){
elem[6].options[elem[6].length] = opt1 ;
elem[7].options[elem[7].length] = opt2 ;
}else if (unitetab[i].type == 'Débit'){
elem[8].options[elem[8].length] = opt1 ;
elem[9].options[elem[9].length] = opt2 ;
}else if (unitetab[i].type == 'Volume'){
elem[10].options[elem[10].length] = opt1 ;
elem[11].options[elem[11].length] = opt2 ;
}
}
elem[0].options[0].selected=true ;
elem[1].options[0].selected=true ;
elem[2].options[0].selected=true ;
elem[3].options[0].selected=true ;
elem[4].options[0].selected=true ;
elem[5].options[0].selected=true ;
elem[6].options[0].selected=true ;
elem[7].options[0].selected=true ;
elem[8].options[0].selected=true ;
elem[9].options[0].selected=true ;
elem[10].options[0].selected=true ;
elem[11].options[0].selected=true ;
}

function roundFloat(x) {
	x = parseFloat(x);
	if ( (x>0 && (x >= 100000 || x < 0.0001)) || (x<0 && (x <= -100000 || x > -0.0001))) {return x.toExponential(3);}
	else {
		if(x>0){
			if (x >= 100) return x.toFixed(2);
			if (x < 100) return x.toFixed(6);
		}else{
			if (x <= 100) return x.toFixed(2);
			if (x > 100) return x.toFixed(6);
		}
	}
}