function setapr(y) {
             document.mort_form.apr.value=y;
          }

          function setPrice(y) {
             if ( checkvalue(y) ) {
                document.mort_form.price.value=y;
                calc_values();
             }
          }

          function checkvalue(x,n){
             if ( x.value==0 || x.value=="" || x.value.length==0 ) {
                alert ("Please enter a number\nlarger than 0 for "+n+".");
                x.focus();
                return false;
             } else 
             	return true;
          }
		
          function calc_payments() {
            if ( checkvalue(document.mort_form.price,"Purchase Price") && 
                 checkvalue(document.mort_form.apr,"APR")   && 
                 checkvalue(document.mort_form.num_payments,"Number of Payments")   && 
                 checkvalue(document.mort_form.yrs,"Years")      )
                    calc_values();
          }

          function calc_values() {
             var princ=document.mort_form.price.value-document.mort_form.down.value;
             var i = (document.mort_form.apr.value/100);
                 i = i/document.mort_form.num_payments.value;
             var v = 1/(i+1);
             var months=document.mort_form.yrs.value*document.mort_form.num_payments.value;
             var t = Math.pow(v,months);
             var u = 1-t;
             var a = u/i;
             var payment = princ/a;
                 payment = Math.floor(payment*100)/100;

             document.mort_form.loan_amt.value=princ;
             document.mort_form.Payments.value=months;
             document.mort_form.Monthly.value=payment;
//             alert ("i="+i+"\nv="+v+"\nt="+t+"\nu="+u+"\na="+a+"\nM: "+payment);
          }