blocks/loancalc/block_loancalc.php

   1 <?php // $Id$
   2
   3 class block_loancalc extends block_base {
   4
   5     function init() {
   6         $this->title = get_string('loancalc','block_loancalc');
   7         $this->content_type = BLOCK_TYPE_TEXT;
   8         $this->version = 2005022100;
   9     }
  10
  11     function get_content() {
  12         global $CFG;
  13
  14         $calc = $CFG->pixpath.'/i/calc.gif';
  15
  16         $this->content->text = '
  17         <script type="text/javascript">
  18         <![CDATA[
  19     function Next()
  20     {
  21         submitScreen("Next");
  22         document.getElementById("vbankform").submit();
  23     }
  24     function Back()
  25     {
  26         submitScreen("Back");
  27         document.getElementById("vbankform").submit();
  28     }
  29
  30     function num_format(x) { // format numbers with two digits
  31     sgn = (x < 0);
  32     x = Math.abs(x);
  33     x = Math.floor((x * 100) + .5);
  34     i = 3;
  35     y = "";
  36     while(((i--) > 0) || (x > 0)) {
  37         y = (x % 10) + y;
  38         x = Math.floor(x / 10);
  39         if(i == 1) {
  40             y = "." + y;
  41         }
  42     }
  43     if(sgn) {
  44         y = "-" + y;
  45     }
  46     return(y);
  47 }
  48 function comp(v) { // general entry point for all cases
  49
  50     // convert all entry fields into variables
  51     x = document.getElementById("vbankform");
  52     pv = parseFloat(x.LOANAMOUNT.value);
  53     lpp = parseFloat(x.LOANPAYPERIOD[x.LOANPAYPERIOD.selectedIndex].value);
  54     if (isNaN(pv) && (v != "pv"))
  55     {
  56         x.LOANAMOUNT.select();
  57         x.LOANAMOUNT.focus();
  58         alert("Numbers only to be entered");
  59         return;
  60     }
  61     fv = parseFloat("0");
  62     yr = parseFloat(x.LOANTERM.value);
  63     if (isNaN(yr) && (v != "np"))
  64     {
  65         x.LOANTERM.select();
  66         x.LOANTERM.focus();
  67         alert("Numbers only to be entered");
  68         return;
  69     }
  70     np = lpp * yr;
  71     pmt = -parseFloat(x.LOANREPAYMENT.value);
  72     if (isNaN(pmt) && (v != "pmt"))
  73     {
  74         x.LOANREPAYMENT.select();
  75         x.LOANREPAYMENT.focus();
  76         alert("Numbers only to be entered");
  77         return;
  78     }
  79     if(x.LOANINTRATE.value == "") {
  80         alert("You must enter an interest rate (ir).");
  81     }
  82     else {
  83         ir = parseFloat(x.LOANINTRATE.value);
  84         if (isNaN(ir))
  85         {
  86             x.LOANINTRATE.select();
  87             x.LOANINTRATE.focus();
  88             alert("Numbers only to be entered");
  89             return;
  90         }
  91         ir = ((ir / lpp) / 100);
  92
  93         // test and compute all cases
  94
  95         if (v == "pv") {
  96             if(ir == 0) {
  97                 pv = -(fv + (pmt * np));
  98             }
  99             else {
 100                 q1 = Math.pow(1 + ir,-np);
 101                 q2 = Math.pow(1 + ir,np);
 102                 pv = -(q1 * (fv * ir - pmt + q2 * pmt))/ir;
 103             }
 104             x.LOANAMOUNT.value = num_format(pv);
 105         }
 106
 107         if (v == "np") {
 108             if(ir == 0) {
 109                 if(pmt != 0) {
 110                     np = - (fv + pv)/pmt;
 111                 }
 112                 else {
 113                     alert("Divide by zero error.");
 114                 }
 115             }
 116             else {
 117                 np = Math.log((-fv * ir + pmt)/(pmt + ir * pv))/ Math.log(1 + ir);
 118             }
 119             if(np == 0) {
 120                 alert("Can\'t compute Number of Periods for the present values.");
 121             }
 122             else {
 123                 np = (np / lpp)
 124                 if (isNaN(np)) {
 125                     alert("The repayment amount is less than the interest. You must increase your repayments to pay off this loan!");
 126                 } else {
 127                     x.LOANTERM.value = num_format(np);
 128                 }
 129             }
 130         }
 131
 132         if (v == "pmt") {
 133             if(ir == 0.0) {
 134                 if(np != 0) {
 135                     pmt = (fv + pv)/np;
 136                 }
 137                 else {
 138                     alert("Divide by zero error.");
 139                 }
 140             }
 141             else {
 142                 q = Math.pow(1 + ir,np);
 143                 pmt = ((ir * (fv + q * pv))/(-1 + q));
 144             }
 145             x.LOANREPAYMENT.value = num_format(pmt);
 146         }
 147
 148
 149     }
 150 } // function comp
 151 ]]>
 152 </script>
 153
 154 <h1></h1>
 155 <form method="post" id="vbankform" action="">
 156             <table>
 157                 <tr>
 158                     <td colspan="2">'.get_string('amountofloan','block_loancalc').'</td>
 159                 </tr>
 160                 <tr>
 161                     <td><input name="LOANAMOUNT" id="LOANAMOUNT" size="17" /></td>
 162                     <td><a href="JavaScript:comp(\'pv\');"><img src="'.$calc.'" alt="calculate" /></a></td>
 163                 </tr>
 164                 <tr>
 165                     <td colspan="2">'.get_string('repaymentamount','block_loancalc').'</td>
 166                 </tr>
 167                 <tr>
 168                     <td><input name="LOANREPAYMENT" id="LOANREPAYMENT" size="17" /></td>
 169                     <td><a href="JavaScript:comp(\'pmt\');"><img src="'.$calc.'" alt="calculate" /></a></td>
 170                 </tr>
 171                 <tr>
 172                     <td colspan="2">'.get_string('loanterm','block_loancalc').'</td>
 173                 </tr>
 174                 <tr>
 175                     <td><input name="LOANTERM" id="LOANTERM" size="17" /></td>
 176                     <td><a href="JavaScript:comp(\'np\');"><img src="'.$calc.'" alt="calculate" /></a></td>
 177                 </tr>
 178                 <tr>
 179                     <td colspan="2">'.get_string('interestrate','block_loancalc').'</td>
 180                 </tr>
 181                 <tr>
 182                     <td><input name="LOANINTRATE" id="LOANINTRATE" size="17" /></td>
 183                     <td></td>
 184                 </tr>
 185                 <tr>
 186                     <td colspan="2">'.get_string('repaymentfreq','block_loancalc').'</td>
 187                 </tr>
 188                 <tr>
 189                     <td>';
 190         $options[52] = get_string('weekly','block_loancalc');
 191         $options[26] = get_string('fortnightly','block_loancalc');
 192         $options[12] = get_string('monthly','block_loancalc');
 193         $this->content->text .= choose_from_menu($options,'LOANPAYPERIOD','12',NULL,NULL,NULL,true);
 194         $this->content->text .= '</td>
 195                     <td></td>
 196                 </tr>
 197             </table>
 198             </form>';
 199         $this->content->footer = '';
 200
 201         return $this->content;
 202
 203     }
 204 }
 205 ?>