function QDPCalculate() 
{
    var _totalprice = 95;
    var _papertarget = 0.4;
    var _postaltarget= 1;
    var _telephonetarget= 8;
    var _cd = 7;
    var _reports = 45;
    var _vat = 20;
    var _discount = 4;
    var num =0;
    
    //cost of survey
    if (document.QDPCalculatorForm._survey[14].checked) //SS
        _totalprice = 500;
    
    //cost of paper
    if (document.QDPCalculatorForm._invigilationPaper.checked)
        
        num = document.QDPCalculatorForm._papertargets.value;
        if(isNaN(num))
        {
            document.QDPCalculatorForm._papertargets.value ="";
            num=0;
        }
        if (num!=0)
            {
                _totalprice += (_papertarget * num)
            }
     
    num=0;
    
    //cost of post
    if (document.QDPCalculatorForm._invigilationPost.checked)
    
        num = document.QDPCalculatorForm._posttargets.value;
        if(isNaN(num))
        {
            document.QDPCalculatorForm._posttargets.value ="";
            num=0;
        }
        if (num!=0)
        {
            _totalprice += (_postaltarget * num)
        } 
        
    num=0;   
        
    //cost of telephone
    if (document.QDPCalculatorForm._invigilationTelephone.checked)
    
        num = document.QDPCalculatorForm._telephonetargets.value;
        if(isNaN(num))
        {
            document.QDPCalculatorForm._telephonetargets.value ="";
            num=0;
        }
        if (num!=0)
        {
            _totalprice += (_telephonetarget * num)
        }
    
    num=0;
    
    //cost of cds
    if (document.QDPCalculatorForm._extracd.checked)
        num = document.QDPCalculatorForm._copiescd.value;
        if(isNaN(num))
        {
            document.QDPCalculatorForm._copiescd.value="";
            num=0;
        }
        if (num!=0)
        {
            _totalprice += (_cd * num)
        }
    num=0;
    
     //cost of printed reports
    if (document.QDPCalculatorForm._extrareport.checked)
        num = document.QDPCalculatorForm._copiesreport.value;
        if(isNaN(num))
        {
            document.QDPCalculatorForm._copiesreport.value="";
            num=0;
        }
        if (num!=0)
        {
            _totalprice += (_reports * document.QDPCalculatorForm._copiesreport.value)
        }
    num=0;
    
    //display values
    var _discountamount = _totalprice * (_discount/100) ;
    var _vatamount = (_totalprice - _discountamount)  * (_vat/100);
    var _grandamount = (_totalprice + _vatamount) - _discountamount;
    
    document.QDPCalculatorForm._QDPTotal.value = _totalprice.toFixed(2) ;
    document.QDPCalculatorForm._QDPVAT.value =  _vatamount.toFixed(2);
    document.QDPCalculatorForm._QDPDiscount.value = "-" + _discountamount.toFixed(2);
    document.QDPCalculatorForm._QDPGrandTotal.value = _grandamount.toFixed(2) ;
        
}



function QDPResetCount(id)
{
    if (id ==1)
    {
        if (document.QDPCalculatorForm._invigilationPaper.checked!=true)  
        {
            document.QDPCalculatorForm._papertargets.value="";
            document.QDPCalculatorForm._papertargets.disabled=true;
        }
        else
        {
            document.QDPCalculatorForm._papertargets.value="0";
            document.QDPCalculatorForm._papertargets.disabled=false;
        }
    }
    if (id==2)
    {
        if (document.QDPCalculatorForm._invigilationPost.checked!=true)  
        {
            document.QDPCalculatorForm._posttargets.value="";
            document.QDPCalculatorForm._posttargets.disabled=true;
        }
        else
        {
            document.QDPCalculatorForm._posttargets.value="0";
            document.QDPCalculatorForm._posttargets.disabled=false;
        }
    }
    
    if  (id==3)
    {
        if (document.QDPCalculatorForm._invigilationTelephone.checked!=true)  
        {
            document.QDPCalculatorForm._telephonetargets.value="";
            document.QDPCalculatorForm._telephonetargets.disabled=true;
        }
        else
        {
            document.QDPCalculatorForm._telephonetargets.value="0";
            document.QDPCalculatorForm._telephonetargets.disabled=false;
        }
    }
       
}     

function QDPResetExtras(id)
{

    if (id==1)
    {
        if (document.QDPCalculatorForm._extracd.checked!=true)  
        {
            document.QDPCalculatorForm._copiescd.value="";
            document.QDPCalculatorForm._copiescd.disabled=true;
        }
        else
        {
            document.QDPCalculatorForm._copiescd.value="0";
            document.QDPCalculatorForm._copiescd.disabled=false;
        }
    }
    else
    {
        if (document.QDPCalculatorForm._extrareport.checked!=true)  
        {
            document.QDPCalculatorForm._copiesreport.value="";
            document.QDPCalculatorForm._copiesreport.disabled=true;
        }
        else
        {
            document.QDPCalculatorForm._copiesreport.value="0";
            document.QDPCalculatorForm._copiesreport.disabled=false;
        }
    }
   
       
}     
      
function QDPResetInvigilation()
{
    if (document.QDPCalculatorForm._survey[14].checked== true) //subject specific
        {
            document.QDPCalculatorForm._invigilationOnline.checked =true;
            
            document.QDPCalculatorForm._invigilationPaper.disabled =true;
            document.QDPCalculatorForm._invigilationPost.disabled =true;
            document.QDPCalculatorForm._invigilationTelephone.disabled =true;
           
            
            document.QDPCalculatorForm._invigilationPaper.checked =false;
            document.QDPCalculatorForm._invigilationPost.checked =false;
            document.QDPCalculatorForm._invigilationTelephone.checked =false;
            
            
            document.QDPCalculatorForm._papertargets.disabled =true;
            document.QDPCalculatorForm._posttargets.disabled =true;
            document.QDPCalculatorForm._telephonetargets.disabled =true;
            
            document.QDPCalculatorForm._papertargets.value = "";
            document.QDPCalculatorForm._posttargets.value = "";
            document.QDPCalculatorForm._telephonetargets.value = "";
            
        }
        else
        {
            document.QDPCalculatorForm._invigilationPaper.disabled =false;
            document.QDPCalculatorForm._invigilationPost.disabled =false;
            document.QDPCalculatorForm._invigilationTelephone.disabled =false;
        }
        //reset totals
        document.QDPCalculatorForm._QDPTotal.value = "";
        document.QDPCalculatorForm._QDPVAT.value = "";
        document.QDPCalculatorForm._QDPDiscount.value = "";
        document.QDPCalculatorForm._QDPGrandTotal.value = "";
        
     
}