// JavaScript Document

//Title: JavaScript for Online Bow Window Polygon Side and Central Angle Calculator
//Author: Joe Bartok
//Date: 2007

function solve_polygon()

{

var F = Math.pow(10,12)
var pi = Math.PI
var deg = 180/pi
var rad = pi/180

var display = "\nbest fit results\n";
var span = document.rafterForm.span.value
var projection = document.rafterForm.projection.value
var bays = document.rafterForm.bays.value

if(span < 12){span = 12};
//if(projection > span) {projection = span/2};
if(bays < 2) {bays = 3 };

var results = "<pre>Results From JavaScript Code\nloop results\n";
		results = results + "\n\n" + " span = " + span + " "
		results = results + "\n" +  " projection = " + projection + " "
		results = results + "\n" +  " bays = " + bays + "\n\n "
        
var half_span = .5*span;
//var theta = .01;
var theta = 1/F;
var limit = .5*(bays - 1);
var i = 0;

var odd_bay_add = 0.5;
var odd_bays = true;

var odd_even  = bays  %2;
if(odd_even == 0){ 
	odd_bays = false;
    limit = .5*bays;
	odd_bay_add = 0.0;
}
   
for (var j=0; j<1000; j++){

	
	var n_sum = 0;
	var d_sum = 0;
	var n_calc = 0;
	var d_calc = 0;
	
	do{
		for (var n=1; n<=limit; n++){
			if(odd_bays == true){
				n_calc = Math.cos(n*theta);
				d_calc = Math.sin(n*theta);
			}else{
				n_calc = Math.cos((2*n - 1)*theta/2)
				d_calc = Math.sin((2*n - 1)*theta/2)
			}
			n_sum = n_sum + n_calc
			d_sum = d_sum + d_calc
		}
		
		
	    if(d_sum == 0){ break;}
		var numerator = half_span/(odd_bay_add + n_sum)
		var denominator = projection/d_sum
		var ratio = numerator/denominator
		var difference = denominator - numerator
		results = results + "\n" + i + " difference = " + difference + " "
		results = results + "\n" + i + " ratio = " + ratio + " "
		results = results + "\n" + i + " theta = " + deg*theta + " "
		i++;
		theta = theta/ratio
		if (ratio < 1){	break;}
	
	} while (difference > 0);
	//if(Math.abs(difference) < .0000000000001){ break;}
	if(Math.abs(difference) < 1/F){ break;}
} 

var radius = .5*((numerator + denominator)/2)/(Math.sin(.5*theta))
var bay_arc = radius*theta
var total_arc = bays*radius*theta


display = display + "\n\n" + " Span derived Side = " + numerator
display = display + "\n" + " Projection derived Side = " + denominator
display = display + "\n" + " Ratio = " + ratio
display = display + "\n" + " Difference = " + difference
display = display + "\n" + " Theta = " + theta*deg
display = display + "\n" + " Radius = " + radius
display = display + "\n" + " Arc Length Per Bay = " + bay_arc
display = display + "\n" + " Total arc length = " + total_arc
display = display + "\n" + " odd bays = " + odd_bays
results = results + display + "</pre>";
Show_Results(results);
}


function Show_Results(val)
{
        var testFrame = document.getElementById("iframe1");
        var doc = testFrame.contentDocument;
        if (doc == undefined || doc == null)
            doc = testFrame.contentWindow.document;
        doc.open();
        doc.write(val);
        doc.close();    
      
}