function showcredit()

{

var credit

credit="Script programmed by Jens T.Saetre"

credit+="\n01022004 First version uploaded"

window.alert(credit);



//var theResponse = window.prompt("Welcome?","Enter your name here.");









}



function Radians(number)

{



var rad



rad=number*Math.PI/180; 

return(rad)



}



function Deg(number)

{



var rad



rad=number*180/Math.PI; 

return(rad)



}









function Calculate_FocalpointandBeamwidth()

{

var FD,Focallength,Diameter;



Diameter=document.Parabol.Diameter.value; 

Diameter=Diameter/100; //converts to meters

FD=document.Parabol.FD.value;



Focallength=FD*Diameter;

FD=Focallength/Diameter;



document.Parabol.Focalpoint.value=formatvalue(Focallength*100, 6);



BeamWidth=2*Deg( Math.atan(1/(2*FD)));



document.Parabol.BeamWidth.value=formatvalue(BeamWidth, 5);



}













function Calculate_FD_BeamWidth()

{

var FD,Focallength,Diameter,BeamWidth;



Diameter=document.Parabol.Diameter.value; 

Diameter=Diameter/100;



Focallength=document.Parabol.Focalpoint.value; 

Focallength=Focallength/100;

FD=Focallength/Diameter;

document.Parabol.FD.value=formatvalue(FD, 4);



BeamWidth=2*Deg( Math.atan(1/(2*FD)));



document.Parabol.BeamWidth.value=formatvalue(BeamWidth, 5);



}









function Calculate_Diameter()

{

var FD,Focallength,Diameter,Depth ;



//Diameter=document.Parabol.Diameter.value; 

Depth  =document.Parabol.Depth.value; 

Depth =Depth /100;

Focallength=document.Parabol.Focalpoint.value; 

Focallength=Focallength/100;

Diameter=Math.sqrt(Focallength*16*Depth);

FD=Focallength/Diameter;

document.Parabol.FD.value=formatvalue(FD, 4);

document.Parabol.Diameter.value=formatvalue(Diameter*100, 4);

Calculate_BeamWidth();

}











function formatvalue(input, rsize) // Desimal avrunding

  {

   var invalid = "**************************";

   var nines = "999999999999999999999999";

   var strin = "" + input;

   var fltin = parseFloat(strin);

   if (strin.length <= rsize) return strin;

   if (strin.indexOf("e") != -1 ||

       fltin > parseFloat(nines.substring(0,rsize)+".4"))

      return invalid.substring(0, rsize);

   var rounded = "" + (fltin + (fltin - parseFloat(strin.substring(0, rsize))));

   return rounded.substring(0, rsize);

}