function validate(field)
{
     var flag1 = "0";

     for(var i = 0; i < field.value.length; i++)//loop through every character in text field
     {
	var ch = field.value.charAt(i);
	if(ch < "0" || ch > "9")
	  {
            if(ch !="." || flag1 == "1"){//only one period is allowed outside of 0 - 9 range
	      alert("This field must be a decimal number!");
	      field.focus();}
	      if(ch == ".")
		flag1 = 1;
	  }
     }


    if (field.value == 0 || field.value.length == 0)
    {
        //alert ("This field can't be 0 or empty!");
        field.value=0.0001;
        field.focus();
    }
}

/*
function calculate(form)
{
 var modifier = 1/(((form.wakedurationms.value/1000)*form.wakesperhour.value)/3600);
 var capRat = form.rating.value;
 var consum = form.consump.value;
 var lifeda = (((capRat/consum)*0.9)*modifier)/24;
 var lifeyr = lifeda/365

 alert("Estimated battery life is: "+ ((Math.round(lifeda*100))/100) +" days, or "+ ((Math.round(lifeyr*100))/100) +" years.");

}
*/

function calculate(form)
{
 var capRat = form.rating.value;
 var modRat = capRat*0.85;

 var onms = form.wakedurationms.value*form.wakesperhour.value;
 var onma = form.consump.value;

 var offms = 3600000-onms;
 var offma = form.offconsump.value;

 var realma=((onma*onms)+(offma*offms))/3600000;

 var lifeda = (modRat/realma)/24;
 var lifeyr = lifeda/365

 alert("Estimated battery life is: "+ ((Math.round(lifeda*100))/100) +" days, or "+ ((Math.round(lifeyr*100))/100) +" years.");

}