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


function nd()
{
	var a=document.n.x.value;
	var b=document.n.m.value;
	var c=document.n.s.value;

	var d=3.14;
 	var e=2.718;
	var f=Math.sqrt((2*d));

//1/s*sqrt2PI=g; -(x-m)^2=h; 2*(s^2)=i; (-(x-m)^2)/(2*(s^2))=j; e^(-(x-m)^2)/(2*(s^2))=k; (1/s*sqrt2PI)*(e^(-(x-m)^2)/(2*(s^2)))=nor

	var g=(c*f);
	var h=Math.pow((a-b),2);
	var i=2*(Math.pow(c,2));
	var j=h/i;
	var k=Math.pow(e,j);

//PDF of NORMAL DISTRIBUTION
	var nor=k/g;
	document.n.n1.value=Math.round(nor*1000)/1000;

//PDF of STANDARD NORMAL DISTRIBUTION
	var x=1/f;
	var y=Math.pow(a,2)/2;
	var z=Math.pow(e,y);
	var res=x*z;
	document.n.n2.value=Math.round(res*1000)/1000;


}