function validate(docname)
{
var i;
var getval=docname.value;

// Validate data:- parse string to check whether it contains
// characters other than numbers and one decimal
var count_deci=0;
var flag=0;
// parse through the data
for(i=0;i<getval.length;i=i+1)
{ if((getval.charAt(i) >= "0" && getval.charAt(i)  <= "9") || (getval.charAt(i) == "."))
	{	// if decimal 
	   if(getval.charAt(i) == ".")
	     {
	      count_deci=count_deci+1;
	      // to check entries of the type X.
	      if(getval.charAt(i+1)=="")
	      { 
	        alert("Wrong entry"); 
	        docname.value="";
	        docname.focus();
	        flag=1;
	        break;
	      }
	     }
	      // check if there is more than one decimal
	      if(count_deci>1)
		   { alert("Illegal Data");
			 docname.value="";
			 docname.focus();
			 flag=1;
			 break;
		   }
	}	   
	// executed if data contains alphabets or special chars
	else
	{ alert("Invalid Entry");
	  docname.value="";
	  docname.focus();
	  flag=1;
	  break;
	}		

}
}

function clearbox(docname)
{
var totalrecords;

// obtain the count of records retrieved
totalrecords=3
for(i=0;i<totalrecords;i++)
docname[i].value="";
docname.area0.focus();
return false;
}

<!--
    function calculatePayment() {
        //princ = form.loanAmount.value - form.dp.value;
        //intRate = (form.rateOfIntrest.value/100) / 12;
		var months = document.aspnetForm.termsYear.value * 12;
		var princp=document.aspnetForm.loanAmount.value*1;
		var intr=document.aspnetForm.rateOfIntrest.value*1;
		if (months!=0 && princp!=0 && intr!=0)
		{
			
			var numerator=princp*Math.pow((1+intr/(12*100)),months);
			var denominator=100*12*(Math.pow((1+intr/(12*100)),months)-1)/intr;
			// var tt = Math.floor((princp*intr)/(1-Math.pow(1+intr,(-1*months)))*100)/100;
			var tt=12*(numerator/(denominator*12));
			ftt=currency(tt);
			  
			document.getElementById('show').innerHTML='Monthly EMI : '+ftt;
			document.getElementById('t_month').innerHTML=months;
			//form.principle.value = princ;
			//form.payments.value = months;
		var details_data="<table width='70%'  style='font-family:tahoma; font-size:11px; border-collapse:collapse; ' cellpadding='0' cellspacing='0'><tr ><td style='background:#EDA55C; color:#ffffff; border:solid 1px #EDA55C; padding:2px'>Month</td><td style='background:#EDA55C; color:#ffffff; border:solid 1px #EDA55C; padding:2px'>Opening Balance</td><td style='background:#EDA55C; color:#ffffff; border:solid 1px #EDA55C; padding:2px'>Monthly EMI</td><td style='background:#EDA55C; color:#ffffff; border:solid 1px #EDA55C; padding:2px'>Intrest</td><td style='background:#EDA55C; color:#ffffff; border:solid 1px #EDA55C; padding:2px'>Princpal</td><td style='background:#EDA55C; color:#ffffff; border:solid 1px #EDA55C; padding:2px'>Closing Balance</td></tr>";
	   var dataEMI=0
	   var o_balance=princp
	   var dataprincp=0
	   var dataintr=0
	   var c_balance=0
	   for(i=1;i<=months;i++)
	   {
	   dataintr=((o_balance*intr)/12)/100;
	   dataprincp=Math.round(tt-dataintr)
	   c_balance=o_balance-dataprincp
	   	details_data+='<tr ><td style="border:solid 1px #EDA55C; padding:2px">'+i+'</td><td style="border:solid 1px #EDA55C; padding:2px">'+o_balance+'</td><td style="border:solid 1px #EDA55C; padding:2px">'+Math.ceil(tt)+'</td><td style="border:solid 1px #EDA55C; padding:2px">'+Math.ceil(dataintr)+'</td><td style="border:solid 1px #EDA55C; padding:2px">'+dataprincp+'</td><td style="border:solid 1px #EDA55C; padding:2px">'+c_balance+'</td></tr>'
		
		o_balance=c_balance
	   }
	   
	   document.getElementById('details').innerHTML=details_data+'</table>';
	   
		}else{
			alert('Please fill all the fields')
		}
    }
function currency( num )
{
   var prefix = "Rs ";
   var suffix = "";
   if ( num < 0 )
   {
       prefix = "(Rs ";
       suffix = ")";
       num = - num;
   }
       var temp = Math.round( num * 100.0 ); // convert to pennies!
       if ( temp < 10 ) return prefix + "0.0" + temp + suffix;
       if ( temp < 100 ) return prefix + "0." + temp + suffix;
	   
       temp = prefix + temp; // convert to string!
	   var diff=temp.length-5
		var fst=temp.substring(3,temp.length-5)
		var snd=temp.substring(diff)
		var dec=snd.substring(3)
		var bdec=snd.substring(0,3)
		var arr = new Array()
		var nlen=fst.length
		for(i=0;Math.round(nlen/2)>0;i++)
		{
			
			arr[i]=fst.substring(nlen-2,nlen)
			nlen=(nlen<0)? 2: nlen; 
			nlen-=2
		}
		var dis=""
		for(i=arr.length-1;i>=0;i--)
		{
			dis+=arr[i]+','
		}
		var maindis=prefix+dis+bdec+'.'+dec
       //return temp.substring(3,temp.length-2) + "." + temp.substring(temp.length-2) + suffix;
	   
	   return maindis;
	  
}