// Target Heart Rate Calculator

function checkform() {
  var strAge = document.heartRate.age.value;

  if (strAge == null || strAge.length == 0) {
    var isNumber = false;
  } else {
    var isNumber = gIsNumber(strAge);
  }
  if ( (strAge == null || strAge.length == 0)) {
    alert('I\'m sorry, we cannot calculate your target heart rate until you have entered your age');
    document.heartRate.age.focus();
    document.heartRate.age.select();
    return false;
  } else if (isNumber == false) {
    alert("We didn't understand your age.\nPlease enter your age again.");
    document.heartRate.age.focus();
    document.heartRate.age.select();
    return false;
  } else if (parseFloat(strAge) <= 0) {
    alert("The unborn stubbornly refuse to listen to recommendations for target heart rates\nPlease enter your age again.");
    document.heartRate.age.focus();
    document.heartRate.age.select();
    return false;
  } else if (parseFloat(strAge) > 119) {
    alert("If you are over 120 years old, we congratulate you, but recommend highly that you discuss this exercise plan with your doctor.");
    document.heartRate.age.focus();
    document.heartRate.age.select();
    return false;
  } else {
    return true;
  }
}

function computeform(obj) {
  var baseNum = 220;
  var secondsSelected = document.heartRate.seconds.selectedIndex;

  if (checkform()) {
      // Vanita Nemali BaseNum is not gender dependent - 3/22/2000 BUGno39670 
      //if (callerForm.Gender[1].checked) baseNum = 222;
      var age = document.heartRate.age.value;
      var maxHR = (baseNum - age);

      document.heartRate.max_thr.value = Math.round(((maxHR * 0.50)/60) * (document.heartRate.seconds.options[secondsSelected].value));
      document.heartRate.min_thr.value = Math.round(((maxHR * 0.75)/60) * (document.heartRate.seconds.options[secondsSelected].value));

      document.heartRate.hrmax.value = Math.round((maxHR/60) * (document.heartRate.seconds.options[secondsSelected].value));

    if (obj.name == "change_focus" ) {document.heartRate.max_thr.focus()}
  }
}

function adBannerCalc(strQuery) {

   var strAge = strGetQueryValue(strQuery, 'Age');
   var len = strAge.length;

     if (len > 0) {
       document.heartRate.age.value = strAge;

       if (checkform(document) ) {
          computeform(document);
       }
     } 

}
// end Target Heart Rate Calculator