The JavaScript Source: Calculators: Advanced Scientific Calculator
Our web spider found the following code snippet at javascript_internet_com and contains information about atan and JavaScript. 
atan(x);
function Round() {
x = form.input.value
if (x == '') alert('Error: Input Required');
else form.input.value = Math.round(x);
function Ran() {
x = form.input.value
form.input.value = Math.random(x);
function Neg () {
x = form.input.value
if (x == '') alert('Error: Input Required');
else x = parseFloat(x) * -1;
function del() {
x = form.input.value
x = (x.substring) - 1
//  End -->
</script>
</HEAD>

<!-- STEP TWO: Insert the onLoad event handler into your BODY tag  -->
<BODY onLoad="document.form.input.focus()">

<!-- STEP THREE: Copy this code into the BODY of your HTML document  -->
<div align="center">
<form name="form" method="post" action="javascript:doit()">
<table
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