function getgas(form) 
{
//$ is a pseudo-label
//alert("init")
  if (form.iadriving.value == "") {form.iadriving.value = 100}
  mymiles = form.iaodoto.value - form.iaodofrom.value
  mymileage = mymiles / form.iagals.value
  mygals = form.iagals.value
//  convert to numeric by subtracting zero
  mygals = mygals - 0
  mydriving = form.iadriving.value
  mydriving = mydriving - 0
//  mycity_mileage = Math.round(mymileage * 100 * (100 - form.iadriving.value) / 100) / 100
//  myhwy_mileage = Math.round(mymileage * 100 * form.iadriving.value / 100) / 100
//  myavg_mileage = Math.round((mycity_mileage + myhwy_mileage) * 100 / 2) / 100
  myhwy_mileage = mymileage
// assume 7 mpg diff between Hwy and City
  mycity_mileage = myhwy_mileage - 7
  myxgals = zgals(myhwy_mileage,mycity_mileage,mygals,mydriving,mymileage)
  myavg_mileage = Math.round(mymiles * 100 / myxgals) / 100
  myb = 0
  if (form.bicity.value > 0){myb = myb + 1}
  if (form.bihwy.value > 0){myb = myb + 1}
  if (myb > 0)
  {
    mybcity = form.bicity.value - 0
    mybhwy = form.bihwy.value - 0
    mybavg_mileage = (mybhwy + mybcity) / 2
  }
//$odofrom
//alert("odofrom")
  writetolayer('sbodofrom',form.iaodofrom.value)
  writetolayer('scodofrom',form.iaodofrom.value)
  writetolayer('sdodofrom',form.iaodofrom.value)
  writetolayer('seodofrom',form.iaodofrom.value)
  writetolayer('sfodofrom',form.iaodofrom.value)
  writetolayer('sgodofrom',form.iaodofrom.value)
  writetolayer('shodofrom',form.iaodofrom.value)
  writetolayer('siodofrom',form.iaodofrom.value)
  writetolayer('sjodofrom',form.iaodofrom.value)
  writetolayer('skodofrom',form.iaodofrom.value)
  writetolayer('slodofrom',form.iaodofrom.value)
//$odoto
//alert("odoto")
  writetolayer('sbodoto',form.iaodoto.value)
  writetolayer('scodoto',form.iaodoto.value)
  writetolayer('sdodoto',form.iaodoto.value)
  writetolayer('seodoto',form.iaodoto.value)
  writetolayer('sfodoto',form.iaodoto.value)
  writetolayer('sgodoto',form.iaodoto.value)
  writetolayer('shodoto',form.iaodoto.value)
  writetolayer('siodoto',form.iaodoto.value)
  writetolayer('sjodoto',form.iaodoto.value)
  writetolayer('skodoto',form.iaodoto.value)
  writetolayer('slodoto',form.iaodoto.value)
//$miles
//alert("miles")
  writetolayer('samiles',mymiles)
  writetolayer('sbmiles',mymiles)
  writetolayer('scmiles',mymiles)
  writetolayer('sdmiles',mymiles)
  writetolayer('semiles',mymiles)
  writetolayer('sfmiles',mymiles)
  writetolayer('sgmiles',mymiles)
  writetolayer('shmiles',mymiles)
  writetolayer('similes',mymiles)
  writetolayer('sjmiles',mymiles)
  writetolayer('skmiles',mymiles)
  writetolayer('slmiles',mymiles)
//$gals
//alert("gals")
  bgals = 0
  if (myb > 0)
  {
    bgals = zgals(mybhwy,mybcity,mygals,mydriving,mymileage)
    writetolayer('sbgals',bgals)
  }
  myzcity = 26
  myzhwy = 33
  cgals = zgals(myzhwy,myzcity,mygals,mydriving,mymileage)
  writetolayer('scgals',cgals)
//28,27,33
  myzcity = 28
  myzhwy = 27
  dgals = zgals(myzhwy,myzcity,mygals,mydriving,mymileage)
  writetolayer('sdgals',dgals)
//32,38,35
  myzcity = 32
  myzhwy = 38
  egals = zgals(myzhwy,myzcity,mygals,mydriving,mymileage)
  writetolayer('segals',egals)
//36,42,49
  myzcity = 36
  myzhwy = 42
  fgals = zgals(myzhwy,myzcity,mygals,mydriving,mymileage)
  writetolayer('sfgals',fgals)
//32,43,48
  myzcity = 32
  myzhwy = 43
  ggals = zgals(myzhwy,myzcity,mygals,mydriving,mymileage)
  writetolayer('sggals',ggals)
//32,43,48
  myzcity = 32
  myzhwy = 43
  hgals = zgals(myzhwy,myzcity,mygals,mydriving,mymileage)
  writetolayer('shgals',hgals)
//35,43,39
  myzcity = 35
  myzhwy = 43
  igals = zgals(myzhwy,myzcity,mygals,mydriving,mymileage)
  writetolayer('sigals',igals)
//48,47,48
  myzcity = 48
  myzhwy = 47
  jgals = zgals(myzhwy,myzcity,mygals,mydriving,mymileage)
  writetolayer('sjgals',jgals)
//60,51,56
  myzcity = 60
  myzhwy = 51
  kgals = zgals(myzhwy,myzcity,mygals,mydriving,mymileage)
  writetolayer('skgals',kgals)
//57,56,57
  myzcity = 57
  myzhwy = 56
  lgals = zgals(myzhwy,myzcity,mygals,mydriving,mymileage)
  writetolayer('slgals',lgals)
//$price
//alert("price")
  if (form.iaprice.value == "") 
  {
    price = form.iaamt.value / mymiles
    writetolayer('saprice',price)
    writetolayer('sbprice',price)
    writetolayer('scprice',price)
    writetolayer('sdprice',price)
    writetolayer('seprice',price)
    writetolayer('sfprice',price)
    writetolayer('sgprice',price)
    writetolayer('shprice',price)
    writetolayer('siprice',price)
    writetolayer('sjprice',price)
    writetolayer('skprice',price)
    writetolayer('slprice',price)
  }
  else
  {
    writetolayer('sbprice',form.iaprice.value)
    writetolayer('scprice',form.iaprice.value)
    writetolayer('sdprice',form.iaprice.value)
    writetolayer('seprice',form.iaprice.value)
    writetolayer('sfprice',form.iaprice.value)
    writetolayer('sgprice',form.iaprice.value)
    writetolayer('shprice',form.iaprice.value)
    writetolayer('siprice',form.iaprice.value)
    writetolayer('sjprice',form.iaprice.value)
    writetolayer('skprice',form.iaprice.value)
    writetolayer('slprice',form.iaprice.value)
  }
//$amt
  if (myb > 0) {bamt = bgals * form.iaprice.value}
  camt = cgals * form.iaprice.value
  damt = dgals * form.iaprice.value
  eamt = egals * form.iaprice.value
  famt = fgals * form.iaprice.value
  gamt = ggals * form.iaprice.value
  hamt = hgals * form.iaprice.value
  iamt = igals * form.iaprice.value
  jamt = jgals * form.iaprice.value
  kamt = kgals * form.iaprice.value
  lamt = lgals * form.iaprice.value
  if (form.iaamt.value == "") 
  {
    amt = form.iaprice.value * form.iagals.value
    writetolayer('saamt',amt)
    if (myb > 0) {writetolayer('sbamt',bamt)}
    writetolayer('scamt',camt)
    writetolayer('sdamt',damt)
    writetolayer('seamt',eamt)
    writetolayer('sfamt',famt)
    writetolayer('sgamt',gamt)
    writetolayer('shamt',hamt)
    writetolayer('siamt',iamt)
    writetolayer('sjamt',jamt)
    writetolayer('skamt',kamt)
    writetolayer('slamt',lamt)
  }
  else
  {
    if (myb > 0) {writetolayer('sbamt',bamt)}
    writetolayer('scamt',camt)
    writetolayer('sdamt',damt)
    writetolayer('seamt',eamt)
    writetolayer('sfamt',famt)
    writetolayer('sgamt',gamt)
    writetolayer('shamt',hamt)
    writetolayer('siamt',iamt)
    writetolayer('sjamt',jamt)
    writetolayer('skamt',kamt)
    writetolayer('slamt',lamt)
  }
//$driving
    writetolayer('sbdriving',form.iadriving.value)
    writetolayer('scdriving',form.iadriving.value)
    writetolayer('sddriving',form.iadriving.value)
    writetolayer('sedriving',form.iadriving.value)
    writetolayer('sfdriving',form.iadriving.value)
    writetolayer('sgdriving',form.iadriving.value)
    writetolayer('shdriving',form.iadriving.value)
    writetolayer('sidriving',form.iadriving.value)
    writetolayer('sjdriving',form.iadriving.value)
    writetolayer('skdriving',form.iadriving.value)
    writetolayer('sldriving',form.iadriving.value)
//$city
  writetolayer('sacity',mycity_mileage)
//$hwy
  writetolayer('sahwy',myhwy_mileage)
//$both
  writetolayer('saavg',myavg_mileage);
  if (myb > 0) {writetolayer('sbavg',mybavg_mileage)}
//$carcost  
}
function zgals(myzhwy,myzcity,mygals,mydriving,mymileage)
{
//alert(myzhwy)
//alert(myzcity)
//alert(mygals)
//alert(mydriving)
//alert(myhwy_mileage)
  myzdiff = myzhwy - myzcity
//alert(myzdiff)
  myhwygals = Math.round(mygals * mymileage * 100 / myzhwy) / 100
//alert(myhwygals)
  mycitygals = Math.round(myzhwy * 100 / myzcity * myhwygals) / 100
//alert(mycitygals)
  mydiffgals = Math.round((mycitygals - myhwygals) * 100) / 100
//alert(mydiffgals)
  mydiffgalspct = Math.round(mydiffgals * 100 * (100 - mydriving) / 100) / 100
//alert(mydiffgalspct)
  myzgals = Math.round((myhwygals + mydiffgalspct) * 100) / 100
//alert(myzgals)
  return myzgals
}