function computeForm(form) { 
if ((form.age.value == null ||
form.age.value.length == 0) || (form.restinghr.value == null ||
form.restinghr.value.length == 0)) { return; }

if (form.sex[0].checked) {
       Item = 0;}
	
      else {Item = 1;} 
       
var maxhr = form.maxhr.value;
if (form.maxhr.value.length == 0 && Item == 0){
 maxhr = 208-parseInt(form.age.value*0.7);}
if (form.maxhr.value.length == 0 && Item == 1){
 maxhr = 208-parseInt(form.age.value*0.7);}
var resthr = form.restinghr.value;
var range = maxhr-resthr;

var easy1 = parseInt(range*0.60) + parseInt(resthr);
var easy2 = parseInt(range*0.75) + parseInt(resthr);
var tempo1 =  parseInt(range*0.85) + parseInt(resthr);
var tempo2 =  parseInt(range*0.90)+ parseInt(resthr);

var vo2max2 =  parseInt(range) + parseInt(resthr);

form.maxhr.value =  maxhr;
form.easyhr.value = easy1+"-"+easy2;
form.tempohr.value =tempo1+"-"+tempo2;
form.vo2maxhr.value = tempo2+"-"+maxhr;


 } 

function clearForm(form) { 
form.age.value = ""; form.restinghr.value = "";
form.easyhr.value = "";form.tempohr.value = ""; 
form.vo2maxhr.value = "";}

browserName = navigator.appName;
browserVer = parseInt(navigator.appVersion);

if (browserVer >= 3) version = "n3";
else {
version = "n2";}
if (version == "n3") {
  // on images
  navb1a_1 = new Image(107, 33);
  navb1a_1.src="images/homeb.jpg";
  navb1b_1 = new Image(107, 33);
  navb1b_1.src="images/prdb.jpg";
  navb1c_1 = new Image(107, 33);
  navb1c_1.src="images/intb.jpg";
  navb1d_1 = new Image(107, 33);
  navb1d_1.src="images/hrb.jpg";
  navb1e_1 = new Image(107, 33);
  navb1e_1.src="images/calb.jpg";
  navb1f_1 = new Image(107, 33);
  navb1f_1.src="images/linkb.jpg";
  // off images
  navb1a_0 = new Image(107, 33);
  navb1a_0.src="images/homea.jpg";
  navb1b_0 = new Image(107, 33);
  navb1b_0.src="images/prda.jpg";
  navb1c_0 = new Image(107, 33);
  navb1c_0.src="images/inta.jpg";
   navb1d_0 = new Image(107, 33);
  navb1d_0.src="images/hra.jpg";
  navb1e_0 = new Image(107, 33);
  navb1e_0.src="images/cala.jpg";
  navb1f_0 = new Image(107, 33);
  navb1f_0.src="images/linka.jpg";
}  
function imgchg(imgst,imgName) {
   if (version == "n3") {
     imgc = eval(imgName + "_" + imgst + ".src");
     document [imgName].src = imgc;
   }


}