function preloadImages()
{
var d=document; if(d.images){ if(!d.PREL) d.PREL=new Array();
var i,j=d.PREL.length,a=preloadImages.arguments; for(i=0; i<a.length; i++)
if (a[i].indexOf("#")!=0){ d.PREL[j]=new Image; d.PREL[j++].src=a[i];}}
}

function cambiapulsante(suff,e)
{
var x=e.srcElement
var nome=x.src.substr(0,x.src.length-6)
x.src = nome+suff+".gif"
} 

function Conversione(form)
{
if (form.frig.value == "" && form.btu.value == "" && form.w.value == "") {
   alert("Bisogna inserire almeno un numero (es. 1500.5) in una casella."); }
else if (isNaN(form.frig.value) || isNaN(form.btu.value) || isNaN(form.w.value)) {
   alert("Bisogna inserire numeri e non lettere."); }
else if (form.frig.value >= "0" ){
   form.btu.value=Math.round(eval(form.frig.value+'*'+3.965),0);
   form.w.value=Math.round(eval(form.frig.value+'/'+0.86),0); }
else if (form.btu.value >= "0" ){
   form.frig.value=Math.round(eval(form.btu.value+'/'+3.965),0);
   form.w.value=Math.round(eval(form.btu.value+'/'+3.412),0); }
else if (form.w.value >= "0" ){
   form.frig.value=Math.round(eval(form.w.value+'*'+0.86),0);
   form.btu.value=Math.round(eval(form.w.value+'*'+3.412),0); }  
}

function IndiceCalore(form)
{
if (isNaN(form.temperatura.value) || isNaN(form.umrel.value)) {
   alert("Bisogna inserire numeri e non lettere."); }
else if (form.temperatura.value == "" || form.umrel.value == "") {
   alert("Bisogna inserire un numero intero (es. 35) nelle caselle Temperatura e Umid. Relativa."); }
else {
   var tC = parseInt(form.temperatura.value);
   var u = parseInt(form.umrel.value);
   if (tC<25 || u<30) {
      alert("Attenzione! Per i valori inseriti il contributo dell'Umid. potrebbe non essere significativo; i calcoli vengono comunque eseguiti.")
   };
   tF = tC*(9/5) + 32 ;
   t2=tF*tF;
   u2=u*u;
   HI= -42.379 + 2.04901523*tF + 10.14333127*u - 0.22475541*tF*u - 6.83783e-3*t2 - 5.481717e-2*u2 + 1.22874e-3*t2*u + 8.5282e-4*tF*u2 - 1.99e-6*t2*u2 ; 
   HI = 5/9*(HI - 32);
   HI = Math.round(HI*10)/10;
   SSI = 1.98*(tF - (0.55 - 0.0055*u)*(tF-58)) - 56.83;
   SSI = 5/9*(SSI - 32);
   SSI = Math.round(SSI*10)/10;
   tK=tC + 273;
   eTs=Math.pow(10,((-2937.4 /tK)-4.9283* Math.log(tK)/Math.LN10 +23.5471));
   eTd=eTs * u/100;
   HX=tC + ((eTd-10)*5/9);
   HX = Math.round(HX*10)/10;
   form.indiceHI.value = parseFloat(HI);
   form.indiceSSI.value = parseFloat(SSI);
   form.indiceHX.value = parseFloat(HX); }
}

function CalcoloFreddoCaldo(form)
{
if (isNaN(form.l1.value) || isNaN(form.l2.value) || isNaN(form.h.value) || isNaN(form.kf.value) || isNaN(form.kc.value)) {
   alert("Bisogna inserire numeri e non lettere."); }
else if (form.l1.value == "" || form.l2.value == "" || form.h.value == "" || form.kf.value == "" || form.kc.value == "") {
   alert("Bisogna inserire un numero (es. 3.5) in tutte le caselle vuote."); }
else {
   form.frig.value=Math.round(eval(form.l1.value+'*'+form.l2.value+'*'+form.h.value+'*'+form.kf.value),0);
   form.btuf.value=Math.round(eval(form.frig.value+'*'+3.965),0);
   form.wf.value=Math.round(eval(form.frig.value+'/'+0.86),0);
   form.cal.value=Math.round(eval(form.l1.value+'*'+form.l2.value+'*'+form.h.value+'*'+form.kc.value),0);
   form.btuc.value=Math.round(eval(form.cal.value+'*'+3.965),0);
   form.wc.value=Math.round(eval(form.cal.value+'/'+0.86),0); }
}