function check(ad)
{
	var ch=ad.value;
	if(isNaN(ch))
	{
		var df=ch.substring(0,(ch.length-1));
		ad.value=df;
	}	
}


function scal()
{
	var ss = parseInt(document.single.ss.value);
	var sf = parseInt(document.single.sf.value);
	
	var spa = Math.round((sf/ss)*1000)/1000;
	document.single.spa.value = spa;
		
	var sp = 1-spa;
	document.single.sp.value = Math.round(sp*1000)/1000;

	if(sf > ss)
	{
	document.single.spa.value = 0;
	document.single.sp.value = 0;
	alert("Number of event occurs should always less than Number of possible outcomes");
	}
}


function mcal()
{
	var a=parseInt(document.multiple.a.value);
	var b=parseInt(document.multiple.b.value);
	var n=parseInt(document.multiple.sm.value);
	
	var pa = Math.round((a/n)*1000)/1000;	
	document.multiple.pa.value = pa;
	document.multiple.pda.value = Math.round((1-pa)*1000)/1000;

	var pb = Math.round((b/n)*1000)/1000;	
	document.multiple.pb.value = pb;
	document.multiple.pdb.value = Math.round((1-pb)*1000)/1000;
	
	var pib = Math.round((pa*pb)*1000)/1000;
	document.multiple.pib.value = pib;

	var pua = pa+pb-pib;
	document.multiple.pua.value = Math.round((pua)*1000)/1000;

	var acb = pib/pb;
	document.multiple.acb.value = Math.round((acb)*1000)/1000;
	
	if(n < a || n < b)
	{
		document.multiple.pa.value = 0;
		document.multiple.pb.value = 0;
		document.multiple.pda.value = 0;
		document.multiple.pdb.value = 0;
		document.multiple.pib.value = 0;
		document.multiple.pua.value = 0;
		document.multiple.acb.value = 0;
		alert("Sample size should be greater than both A and B");
	}

}