var numb = '0123456789.';
function IsValid(parm) {
  if (parm == "") return false;
  for (i=0; i<parm.length; i++) {
    if (numb.indexOf(parm.charAt(i),0) == -1) return false;
  }
  return true;
}
function Round(r)
{
	Value = r * 100;
	Value = Math.round(Value);
	Value = Value / 100;
	return Value.toString();
}
function calculator()
{      
        if (IsValid(document.l_pad_input.ohm_load.value) && IsValid(document.l_pad_input.attenuation.value)) 
		{		
		z = eval(document.l_pad_input.ohm_load.value);
		attenuation = eval(document.l_pad_input.attenuation.value);
		expo = eval(.05 * attenuation * -1);
		R2 = z * (Math.pow(10, expo)) / (1 - Math.pow(10, expo));
		R1 = z - ((R2 * z) / (R2 + z));
		document.l_pad_input.r1.value = Round(R1);
		document.l_pad_input.r2.value = Round(R2);			
		}
		else		
        {
		alert( "Invalid input!" );
		}
}