function gsub_num(el)
	{
		var str=el.value;
		var i, num='';
		myRegExp = /[0-9]/;
		for (i=0;i<str.length;i++) {
			if (myRegExp(str[i])) 
				num = num + str[i];
		}
		el.value = num;
	}
	
function gsub_realnum(el)
	{
		var str=el.value;
		var i, num='';
		var n_titik=0;
		myRegExp = /[0-9]/ ;
		for (i=0;i<str.length;i++) {
			if (str[i]=="." && n_titik==0)
			{
				num = num + str[i];
				n_titik+=1;
				continue;
			}
			if (myRegExp(str[i])) 
				num = num + str[i];
		}
		el.value = num;
	}
	
function gsub_alpha_num(el)
	{
		var str=el.value;
		var i, num='';
		
		myRegExp = /[a-z\ \_\-A-Z0-9]/ ;
		for (i=0;i<str.length;i++) {
			if (myRegExp(str[i])) 
				num = num + str[i];
		}
		el.value = num;
	}