New block for student loan calculation. Doesn't contain db tables.

2005-08-16 01:45:42 +00:00
parent 06ba0b0452
commit 3e920f36ff
3 changed files with 218 additions and 0 deletions
@@ -0,0 +1,206 @@
+<?php
+
+class block_student_loan_calc extends block_base {
+
+    function init() {
+        $this->title = get_string('studentloancalc','block_student_loan_calc');
+        $this->content_type = BLOCK_TYPE_TEXT;
+        $this->version = 2005022100;
+    }
+
+    function get_content() {
+        global $CFG;
+
+        $calc = $CFG->pixpath.'/i/calc.gif';
+        
+        $this->content->text = '
+        <script language="JavaScript">
+<!--
+	function Next()
+	{
+		submitScreen("Next");
+		document.vbankform.submit();
+	}
+	function Back()
+	{
+		submitScreen("Back");
+		document.vbankform.submit();
+	}
+
+	function num_format(x) { // format numbers with two digits
+	sgn = (x < 0);
+	x = Math.abs(x);
+	x = Math.floor((x * 100) + .5);
+	i = 3;
+	y = "";
+	while(((i--) > 0) || (x > 0)) {
+		y = (x % 10) + y;
+		x = Math.floor(x / 10);
+		if(i == 1) {
+			y = "." + y;
+		}
+	}
+	if(sgn) {
+		y = "-" + y;
+	}
+	return(y);
+}
+function comp(v) { // general entry point for all cases
+
+	// convert all entry fields into variables
+	x = document.vbankform;
+	pv = parseFloat(x.LOANAMOUNT.value);
+	lpp = parseFloat(x.LOANPAYPERIOD[x.LOANPAYPERIOD.selectedIndex].value);
+	if (isNaN(pv) && (v != "pv"))
+	{
+		x.LOANAMOUNT.select();
+		x.LOANAMOUNT.focus();
+		alert("Numbers only to be entered");
+		return;
+	}
+	fv = parseFloat("0");
+	yr = parseFloat(x.LOANTERM.value);
+	if (isNaN(yr) && (v != "np"))
+	{
+		x.LOANTERM.select();
+		x.LOANTERM.focus();
+		alert("Numbers only to be entered");
+		return;
+	}
+	np = lpp * yr;
+	pmt = -parseFloat(x.LOANREPAYMENT.value);
+	if (isNaN(pmt) && (v != "pmt"))
+	{
+		x.LOANREPAYMENT.select();
+		x.LOANREPAYMENT.focus();
+		alert("Numbers only to be entered");
+		return;
+	}
+	if(x.LOANINTRATE.value == "") {
+		alert("You must enter an interest rate (ir).");
+	}
+	else {
+		ir = parseFloat(x.LOANINTRATE.value);
+		if (isNaN(ir))
+		{
+			x.LOANINTRATE.select();
+			x.LOANINTRATE.focus();
+			alert("Numbers only to be entered");
+			return;
+		}
+		ir = ((ir / lpp) / 100);
+
+		// test and compute all cases
+
+		if (v == "pv") {
+			if(ir == 0) {
+				pv = -(fv + (pmt * np));
+			}
+			else {
+				q1 = Math.pow(1 + ir,-np);
+				q2 = Math.pow(1 + ir,np);
+				pv = -(q1 * (fv * ir - pmt + q2 * pmt))/ir;
+			}
+			x.LOANAMOUNT.value = num_format(pv);
+		}
+
+		if (v == "np") {
+			if(ir == 0) {
+				if(pmt != 0) {
+					np = - (fv + pv)/pmt;
+				}
+				else {
+					alert("Divide by zero error.");
+				}
+			}
+			else {
+				np = Math.log((-fv * ir + pmt)/(pmt + ir * pv))/ Math.log(1 + ir);
+			}
+			if(np == 0) {
+				alert("Can\'t compute Number of Periods for the present values.");
+			}
+			else {
+				np = (np / lpp)
+				if (isNaN(np)) {
+					alert("The repayment amount is less than the interest. You must increase your repayments to pay off this loan!");
+				} else {
+					x.LOANTERM.value = num_format(np);
+				}
+			}
+		}
+
+		if (v == "pmt") {
+			if(ir == 0.0) {
+				if(np != 0) {
+					pmt = (fv + pv)/np;
+				}
+				else {
+					alert("Divide by zero error.");
+				}
+			}
+			else {
+				q = Math.pow(1 + ir,np);
+				pmt = ((ir * (fv + q * pv))/(-1 + q));
+			}
+			x.LOANREPAYMENT.value = num_format(pmt);
+		}
+
+
+	}
+} // function comp
+//-->
+			</script>
+<title></title>
+</head>
+
+<body>
+<h1></h1>
+<form method="post" id="vbankform" name="vbankform">
+			<table>
+                <tr>
+					<td colspan="2">'.get_string('amountofloan','block_student_loan_calc').'</td>
+                </tr>
+				<tr>
+					<td><input name="LOANAMOUNT" id="LOANAMOUNT" size="17"></td>
+					<td><a href="JavaScript:comp(\'pv\');"><img src="'.$calc.'" alt="calculate" border="0"></a></td>
+				</tr>
+				<tr>
+					<td colspan="2">'.get_string('repaymentamount','block_student_loan_calc').'</td>
+				</tr>
+				<tr>
+					<td><input name="LOANREPAYMENT" id="LOANREPAYMENT" size="17"></td>
+					<td><a href="JavaScript:comp(\'pmt\');"><img src="'.$calc.'" alt="calculate" border="0"></a></td>
+				</tr>
+				<tr>
+					<td colspan="2">'.get_string('loanterm','block_student_loan_calc').'</td>
+				</tr>
+				<tr>
+					<td><input name="LOANTERM" id="LOANTERM" size="17"></td>
+					<td><a href="JavaScript:comp(\'np\');"><img src="'.$calc.'" alt="calculate" border="0"></a></td>
+				</tr>	
+				<tr>
+					<td colspan="2">'.get_string('interestrate','block_student_loan_calc').'</td>
+				</tr>
+				<tr>
+					<td><input name="LOANINTRATE" id="LOANINTRATE" size="17"></td>
+					<td></td>
+				</tr>	
+				<tr>
+					<td colspan="2">'.get_string('repaymentfreq','block_student_loan_calc').'</td>
+                </tr>
+					<td>';
+        $options[52] = get_string('weekly','block_student_loan_calc');
+        $options[26] = get_string('fortnightly','block_student_loan_calc');
+        $options[12] = get_string('monthly','block_student_loan_calc');
+        $this->content->text .= choose_from_menu($options,'LOANPAYPERIOD','12',NULL,NULL,NULL,true);
+        $this->content->text .= '</td>
+					<td></td>
+				</tr>
+			</table>
+			</form>';
+
+        return $this->content;
+
+    }
+}
+?>
@@ -0,0 +1,12 @@
+<?
+$string['studentloancalc'] = 'Student loan calculator';
+$string['amountofloan'] = 'Amount of loan';
+$string['repaymentamount'] = 'Repayment amount';
+$string['loanterm']  = 'Loan term (years)';
+$string['interestrate'] = 'Interest rate';
+$string['repaymentfreq'] = 'Repayment frequency';
+$string['weekly'] = 'Weekly';
+$string['fortnightly']  = 'Fortnightly';
+$string['monthly'] = 'Monthly';
+
+?>