function round(number,X) {
    return Math.round(number*Math.pow(10,X))/Math.pow(10,X);
}

function changeType() {
		var nozzle = document.forms[0].nozzle;
		var fan = document.forms[0].fan;
		var type   = document.forms[0].calctype.options[document.forms[0].calctype.selectedIndex].text;
  
		if (type == "ULV")	{
		
			// add nozzle options for ULV
  		nozzle.options.length = 0;
  	  var option = new Option("2","2");
	  	nozzle.options[0] = option;
  	  option = new Option("4","4");
	  	nozzle.options[1] = option;
  	 
			// add additional fan option for ULV
			fan.options.length = 0;
  	  option = new Option("65","65");
	  	fan.options[0] = option;
  	  option = new Option("80","80");
	  	fan.options[1] = option;
  	  option = new Option("110","110");
	  	fan.options[2] = option;
  	  
		}
		else { // water
		  
			nozzle.options.length = 0;
  	  var option = new Option("2","2");
	  	nozzle.options[0] = option;
  	  option = new Option("4","4");
	  	nozzle.options[1] = option;
 			option = new Option("6","6");
	  	nozzle.options[2] = option;
  	  option = new Option("8","8");
	  	nozzle.options[3] = option;
  	  option = new Option("10","10");
	  	nozzle.options[4] = option;
  	  option = new Option("15","15");
	  	nozzle.options[5] = option;
  	  option = new Option("20","20");
	  	nozzle.options[6] = option;
  	  option = new Option("30","30");
	  	nozzle.options[7] = option;
			
			fan.options.length = 0;
  	  option = new Option("40","40");
	  	fan.options[0] = option;
  	  option = new Option("65","65");
	  	fan.options[1] = option;
  	  option = new Option("80","80");
	  	fan.options[2] = option;
  	  option = new Option("110","110");
	  	fan.options[3] = option;
  	  
		}
		
			 
}

function doCalculation(formptr)
{ 
  var basefigure = 0;
  var vararr    = new Array(3);
  vararr[0] = new Array(8);
  vararr[1] = new Array(8);
  vararr[2] = new Array(8);
    
  var ansarr    = new Array(3);
  var d1,d2,vmd,span;
  
  ansarr[0] = new Array(2);
  ansarr[1] = new Array(2);
  ansarr[2] = new Array(2);
  
  var airspeed	= formptr.airspeed.value;
  var nozzle	= formptr.nozzle.value;
  var fan		= formptr.fan.value;
  var airstream = formptr.airstream.value;
  var type      = formptr.calctype.options[formptr.calctype.selectedIndex].text;
       
  if (nozzle == 0 || fan == 0 || airspeed < 95 || airspeed > 145 || airstream < 0 || airstream > 110)
  {
    alert("Please fill in all the fields. Make sure Airspeed is between 95 and 145 and Nozzle Angle between 0 and 110.");
  }
  else
  {
  if(type == "Water")
  {
    vararr[0][0] = 339;
    vararr[0][1] = -4.81;
    vararr[0][2] = 5.92;
    vararr[0][3] = -1.56;
    vararr[0][4] = -2.63;
    vararr[0][5] = 0.0587;
    vararr[0][6] = -0.0149;
    vararr[0][7] = 0.0113;
   
    vararr[1][0] = 701;
    vararr[1][1] = -14;
    vararr[1][2] = 25.1;
    vararr[1][3] = -3.06;
    vararr[1][4] = -4.62;
    vararr[1][5] = 0.139;
    vararr[1][6] = -0.148;
    vararr[1][7] = 0.0189;
    
    vararr[2][0] = 994;
    vararr[2][1] = -22.4;
    vararr[2][2] = 88;
    vararr[2][3] = -4.57;
    vararr[2][4] = -5.66;
    vararr[2][5] = 0.184;
    vararr[2][6] = -0.804;
    vararr[2][7] = 0.028;

    document.all.resultComment.innerHTML = "Results Based on Water at 3bar";	
   }
   else
   {
    vararr[0][0] = 350
    vararr[0][1] = -25.8
    vararr[0][2] = -12.9
    vararr[0][3] = -0.084
    vararr[0][4] = -3.3
    vararr[0][5] = 0.26
    vararr[0][6] = 0.204
    vararr[0][7] = -0.00014
  
    vararr[1][0] = 608
    vararr[1][1] = -38.9
    vararr[1][2] = -4.1
    vararr[1][3] = -0.511
    vararr[1][4] = -5.43
    vararr[1][5] = 0.425
    vararr[1][6] = 0.267
    vararr[1][7] = 0.00082
 
    vararr[2][0] = 817
    vararr[2][1] = -49
    vararr[2][2] = 2.9
    vararr[2][3] = -0.523
    vararr[2][4] = -6.8
    vararr[2][5] = 0.616
    vararr[2][6] = 0.224
    vararr[2][7] = -0.00642

   	document.all.resultComment.innerHTML = "Results Based on 100% DC-TRON at 3bar";
  }
  
  basefigure = airspeed * nozzle * fan;
    
  for(var i = 0; i < 3; i++)
  {
    ansarr[i][0] = vararr[i][0] + (vararr[i][1] * Math.sqrt(fan)) + (vararr[i][2] * Math.sqrt(nozzle)) + (vararr[i][3] * airspeed);
    ansarr[i][1] = (vararr[i][4] * airstream) + (vararr[i][5] * airstream * Math.sqrt(fan)) +(vararr[i][6] * airstream * Math.sqrt(nozzle)) + (vararr[i][7] * airstream * airspeed)
   }
 
  if (basefigure != 0)
  {    
    d1  = round(ansarr[0][0] + ansarr[0][1],0);
    vmd = round(ansarr[1][0] + ansarr[1][1],0);
    d2  = round(ansarr[2][0] + ansarr[2][1],0);
    span = round((d2 - d1)/vmd,2);
  }
	
//		  document.all.dropletsize.innerHTML = basefigure; 
      document.all.d1.innerHTML   = d1;  
      document.all.vmd.innerHTML  = vmd;  
      document.all.d2.innerHTML   = d2;  
      document.all.thespan.innerHTML = span;     
   
  }
  
  return false;
}