checked = false;  
function check()
{
/*
var j=0;
while (j<= 10)
{
 var rr=document.getElementById("mcat"+j).name; //alert(rr);
 var l=rr.length;
 alert(l);
 j++;
}
*/
 
    if (checked == false){checked = true}else{checked = false}  
    for (var i = 0; i < document.getElementById('f1').elements.length; i++) {  
    document.getElementById('f1').elements[i].checked = checked;  
    }  
     
return false;
}