/* speedclc.js -- created by john russell, ve3ll@rac.ca
  validated with JSlint 2010 02 01 */
  
cf=3600/(5280*12);// inch per sec to mph
sf=null;time=null;dist=null;vel=null;

function roundoff(x,y){ //generalized procedure
scale=Math.pow(10,y);return Math.round(x * scale)/scale;}

/* added scale/track caclulation for industrials May 09 2007
  es is engine scale
  ts is scale of track
  proto is prototype result in inches */
function calcForm(){
  el=document.getElementById('es');
  sc=el.options[el.selectedIndex].text;
  es=sc.substring(sc.indexOf(":")+1, sc.length);
  el=document.getElementById('ts');
  sc=el.options[el.selectedIndex].text;
  ts=sc.substring(sc.indexOf(":")+1, sc.length);
  proto=56.5*es/ts;protom=proto*2.54/100;
  document.getElementById('proto').value=roundoff(proto,1);
  document.getElementById('protom').value=roundoff(protom,2);}

/* -- compute scale speeds
  clcd is input control for distance (in inches),
  clct is input control for time (in seconds),
  clcs is select controlscale (text - 1:x)
  clcv is output in scale mph (for report a set of mphs for 1,2,...12 secs)
  access is thru the form element id 'clc' */

function about(id){
alert('SpeedCalc version 4.1 written by John Russell.\n' +
    'Feel free to copy speedclc.js for your own use.');
document.getElementById(id+'d').focus();}

function clrForm(id){
sf=null;time=null;dist=null;vel=null;
document.getElementById(id+'d').value=" ";
document.getElementById(id+'t').value=" ";
document.getElementById(id+'v').value=" ";
document.getElementById(id+'d').focus();}

function testDist(id){
if(dist.length<1){
  alert("You must set distance!");
  document.getElementById(id+'d').focus();return false;}
if(isNaN(dist)===true){
  alert("Distance must be a number!");
  document.getElementById(id+'d').focus();return false;}
if(dist<0.1){
  alert("Distance must be positive!");
  document.getElementById(id+'d').focus();return false;}
return true;}

function testTime(id){
if(time.length<1){
  alert("You must set time!");
  document.getElementById(id+'t').focus();return false;}
if(isNaN(time)===true){
  alert("Time must be a number!");
  document.getElementById(id+'t').focus();return false;}
if(time<0.1){
  alert("Time must be positive!");
  document.getElementById(id+'t').focus();return false;}
return true;}

function testVel(id){
if(vel.length<1){
  alert("You must set speed!");
  document.getElementById(id+'v').focus();return false;}
if(isNaN(vel)===true){
  alert("Speed must be a number!");
  document.getElementById(id+'v').focus();return false;}
if(vel<0.1){
  alert("Speed must be positive!");
  document.getElementById(id+'v').focus();return false;}
return true;}

function distx(id){ //validate before math
time=document.getElementById(id+'t').value;
vel=document.getElementById(id+'v').value;
el=document.getElementById(id+'s');
sc=el.options[el.selectedIndex].text;
sf=sc.substring(sc.indexOf(":")+1,sc.length);
if(testTime(id)===false){return;}
if(testVel(id)===false){return;}
document.getElementById(id+'d').value=roundoff(vel*time/(cf*sf),1);
document.getElementById(id+'d').focus();}

function speed(id){ //validate before math
dist=document.getElementById(id+'d').value;
time=document.getElementById(id+'t').value;
el=document.getElementById(id+'s');
sc=el.options[el.selectedIndex].text;
sf=sc.substring(sc.indexOf(":")+1,sc.length);
if(testDist(id)===false){return;}
if(testTime(id)===false){return;}
document.getElementById(id+'v').value=roundoff(dist/time*(cf*sf),1);
document.getElementById(id+'d').focus();}

function timex(id){ //validate before math
dist=document.getElementById(id+'d').value;
vel=document.getElementById(id+'v').value;
el=document.getElementById(id+'s');
sc=el.options[el.selectedIndex].text;
sf=sc.substring(sc.indexOf(":")+1,sc.length);
if(testDist(id)===false){return;}
if(testVel(id)===false){return;}
document.getElementById(id+'t').value=roundoff(dist/vel*(cf*sf),1);
document.getElementById(id+'d').focus();}

function report(id){
dist=document.getElementById(id+'d').value;
if(testDist(id)===false){return;}
el=document.getElementById(id+'s');
sc=el.options[el.selectedIndex].text;
sf=sc.substring(sc.indexOf(":")+1,sc.length);
msg='<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">\n';
msg+='<html><head><title>Speed Chart for '+sc+' Scale<\/title>\n';
msg+='<style type="text/css">\nbody{background:linen}\n';
msg+='h1,h3, div{text-align:center}\n';
msg+='table{margin:auto}\n<\/style>\n';
msg+='<meta http-equiv="Content-Type" content="text/html;charset=iso-8859-1">\n';
msg+='<\/head><body><h1>Speed Chart for '+sc+' Scale<\/h1>\n';
msg+='<h3>Timed distance is '+dist+' inches<\/h3>\n<div><table>\n';
msg+='<tr><th>Time [sec]<\/th><th>Speed [mph]<\/th><\/tr>';
for(rt=1;rt<=12;rt++){
  spd=roundoff(dist/rt*(cf*sf),1);// calc for one unit
  msg+='<tr><th>'+rt+'<\/th><th>'+spd+'</th><\/tr>\n';
  }
msg+='<\/table><\/div><\/body><\/html>\n';document.write(msg);}