var irate, mi, cmi, years, tprinc, princ, paym, cpaym, osp,v,downp,downr,comp;
function calcPaym(cdn){
   tprinc = round2d(parseFloat(document.smpc.tprinc.value));
   downp = .01*parseFloat(document.smpc.downp.value);
   downr = ceil2d(downp*tprinc);
   princ = tprinc-downr;
   
   document.smpc.princ.value = fmt2d(princ,0);
   document.smpc.downr.value = fmt2d(downr,0);
     
   irate = .01*parseFloat(document.smpc.percent.value);
   years=parseFloat(document.smpc.years.value);
   term = parseFloat(document.smpc.term.value);
   if(term > years)term=years;
   
   if (term==0 || years==0||irate<.0001||princ<1)
   {alert("values must be numeric");}
   else 
   {
       if(cdn)mi = Math.pow(1+ irate/2,1/6) 
       else   mi = 1+(irate/12);
       v = 1/mi;
       paym = ceil2d(princ*(mi-1)/(1-Math.pow(mi,-(years*12))));
       osp = (princ-(v*paym*(1-Math.pow(v,12*term)))/(1-v))/Math.pow(v,12*term);
       if(osp<0)osp = 0;
       
       document.smpc.paym.value=fmt2d(paym,0);
       document.smpc.owed.value = fmt2d(osp,0);
   }
}
function round2d(n){return(.01* Math.round(100*n));}
function floor2d(n){return(.01* Math.floor(100*n));}
function ceil2d(n){return(.01* Math.ceil(100*n));}
// format number n as string width w with 2 decimal places
function fmt2d(n,w)
{
   var work,dp,sl,dl;
   
   work = ""+floor2d(n); // force only 2 decimals
   sl=work.length;
   
   if(-1 == (dp = work.indexOf(".")))work=work+".00";
   else if(3 > sl-dp)work = work+".00".substring(sl-dp,3);
   sl = work.length;
   if(0 != w && w !=sl)
      if(w<sl){work = "*";for(sl=1;sl<w;sl++)work=work+"*";}
      else for(;sl<w;sl++)work=" "+work; 
   return work;
}