/*
Science & Engineering Encyclopaedia. Copyright Dirac Delta Consultants Ltd. 2001-2002

No part of this document may be reproduced or transmitted in any form or by any mean, electronic or mechanical, including printing, placing on the internet or by any information storage and retrieval system without permission from the Publisher in writing
*/

var xnm=4
var ynm=1
xnme = new Array(xnm)
ynme = new Array(ynm)
xtxt = new Array(xnm)
ytxt = new Array(ynm)
xunt = new Array(xnm)
yunt = new Array(ynm)
xvrb = new Array(xnm)
yvrb = new Array(ynm)


frm="qw"
scrp="natural"
ttle="Quarter Wave Tube"
xnme[1]="c"
xtxt[1]="Speed of sound, c"
xunt[1]="ms<sup>-1</sup>"
xnme[2]="lb"
xtxt[2]="Length of side branch, L<sub>b</sub>"
xunt[2]="m"
xnme[3]="r"
xtxt[3]="Radius of main duct, r"
xunt[3]="m"
xnme[4]="rb"
xtxt[4]="Radius of side branch, r<sub>b</sub>"
xunt[4]="m"


ynme[1]="fn"
ytxt[1]="Resonant frequency, f<sub>r</sub>"
yunt[1]="Hz"

var d1 = [];
var dataseries=[];
var num_series=0;

function natural()
{
	xvrb[1]=parseFloat(document.qw.c.value)
	xvrb[2]=parseFloat(document.qw.lb.value)
	xvrb[3]=parseFloat(document.qw.r.value)
	xvrb[4]=parseFloat(document.qw.rb.value)


	yvrb[1]=xvrb[1]/(4*xvrb[2])

	document.qw.fn.value=yvrb[1]

	datay = yvrb[1]
	datax="Freq"
	sb=xvrb[4]*xvrb[4]*Math.PI
	s=xvrb[3]*xvrb[3]*Math.PI

	fr=yvrb[1]

	for (x=1 ; x<1000 ; x=x+1)
	{
		y = 10*Math.log(1+Math.pow(sb/(2*s),2)*Math.pow(Math.tan(Math.PI*x/(2*fr)),2))/Math.log(10)
	 	datay = datay + "," + y
		datax= datax + "," + x
		d1.push([x, y]);
	} 
	/*document.DDPlot.newData(datax,datay)*/
	dataseries.push({label:fr,data:d1,color:num_series});
	num_series++;
	d1=[];
	
	$.plot($("#placeholder"), dataseries);
}