# Thread: [JAVASCRIPT] - Calculating Pi

1. ## [JAVASCRIPT] - Calculating Pi

I converted this from VB6 into Javascript:

Code:
```  function CalculatePi() // Calculates Pi by counting all the points around a circle making it easier and randomizing it.
{
var TOTAL_POINTS = new Number(1000000); //  points in pi (3.14159)
var x = new Number();
var y = new Number();
var points_in_circle = new Number();
var i = new Number();
for (i;i<=TOTAL_POINTS;i++) // for i = 0 to 1000000 increasing by 1 increment every loop
{
x = Math.random() * 1; // random x between 0 and 1
y = Math.random() * 1; // random y between 0 and 1
if (x * x + y * y < 1) // if both randomized to 0
{
points_in_circle = points_in_circle + 1; // increase points_in_circle
}
}
return 4 * points_in_circle / TOTAL_POINTS; // return answer to user
}```

2. ## Re: [JAVASCRIPT] - Calculating Pi

Please try this code, To how to calculate PI using javascript.

Code:
```<html>
<title>Pi</title>
<script type="text/javascript">
mess = "";
Base = Math.pow(10, 11);
cellSize = Math.floor(Math.log(Base) / Math.LN10);
a = Number.MAX_VALUE;
MaxDiv = Math.floor(Math.sqrt(a));
function makeArray(n, aX, Integer) {
var i = 0;
for (i = 1; i < n; i++) aX[i] = null;
aX[0] = Integer
}
function isEmpty(aX) {
var empty = true
for (i = 0; i < aX.length; i++) if (aX[i]) {
empty = false;
break
}
return empty
}
function Add(n, aX, aY) {
carry = 0
for (i = n - 1; i >= 0; i--) {
aX[i] += Number(aY[i]) + Number(carry);
if (aX[i] < Base) carry = 0;
else {
carry = 1;
aX[i] = Number(aX[i]) - Number(Base)
}
}
}
function Sub(n, aX, aY) {
for (i = n - 1; i >= 0; i--) {
aX[i] -= aY[i];
if (aX[i] < 0) {
if (i > 0) {
aX[i] += Base;
aX[i - 1]--
}
}
}
}
function Mul(n, aX, iMult) {
carry = 0;
for (i = n - 1; i >= 0; i--) {
prod = (aX[i]) * iMult;
prod += carry;
if (prod >= Base) {
carry = Math.floor(prod / Base);
prod -= (carry * Base)
} else carry = 0;
aX[i] = prod
}
}
function Div(n, aX, iDiv, aY) {
carry = 0;
for (i = 0; i < n; i++) {
currVal = Number(aX[i]) + Number(carry * Base);
theDiv = Math.floor(currVal / iDiv);
carry = currVal - theDiv * iDiv;
aY[i] = theDiv
}
}
function arctan(iAng, n, aX) {
iAng_squared = iAng * iAng;
k = 3;
sign = 0;
makeArray(n, aX, 0);
makeArray(n, aAngle, 1);
Div(n, aAngle, iAng, aAngle);
while (!isEmpty(aAngle)) {
Div(n, aAngle, iAng_squared, aAngle);
Div(n, aAngle, k, aDivK);
else Sub(n, aX, aDivK);
k += 2;
sign = 1 - sign
}
mess += "aArctan=" + aArctan + "<br>"
}
function calcPI(numDec) {
var ans = "";
t1 = new Date();
numDec = Number(numDec) + 5;
iAng = new Array(10);
coeff = new Array(10);
arrayLength = Math.ceil(1 + numDec / cellSize);
aPI = new Array(arrayLength);
aArctan = new Array(arrayLength);
aAngle = new Array(arrayLength);
aDivK = new Array(arrayLength);
coeff[0] = 4;
coeff[1] = -1;
coeff[2] = 0;
iAng[0] = 5;
iAng[1] = 239;
iAng[2] = 0;
makeArray(arrayLength, aPI, 0);
makeArray(arrayLength, aAngle, 0);
for (var i = 0; coeff[i] != 0; i++) {
arctan(iAng[i], arrayLength, aArctan);
Mul(arrayLength, aArctan, Math.abs(coeff[i]));
if (coeff[i] > 0) Add(arrayLength, aPI, aArctan);
else Sub(arrayLength, aPI, aArctan)
}
Mul(arrayLength, aPI, 4);
sPI = "";
tempPI = "";
for (i = 0; i < aPI.length; i++) {
aPI[i] = String(aPI[i]);
if (aPI[i].length < cellSize && i != 0) {
while (aPI[i].length < cellSize) aPI[i] = "0" + aPI[i]
}
tempPI += aPI[i]
}
for (i = 0; i <= numDec; i++) {
if (i == 0) sPI += tempPI.charAt(i) + ".<br>";
else {
if (document.getElementById("cbCount").checked) addcount = " (" + (i) + ")";
else addcount = "";
if (document.getElementById("cbSpace").checked) thespace = " ";
else thespace = "";
if ((i) % 50 == 0 && i != 0) sPI += tempPI.charAt(i) + addcount + "<br>";
else if (i % 5 == 0) sPI += tempPI.charAt(i) + thespace;
else sPI += tempPI.charAt(i)
}
}
ans += ("PI (" + numDec + ")=" + sPI + "<br>");
ans += ("Win PI=<br>3.1415926535897932384626433832795<br>");
t2 = new Date();
timeTaken = (t2.getTime() - t1.getTime()) / 1000;
ans += "It took: " + timeTaken + " seconds";
var myDiv = document.getElementById("d1");
myDiv.innerHTML = ans
}
</script>
<body>
<h1>
Pi Machin
</h1>
<form name="" id="" method="post" action="" enctype="text/plain" onsubmit="calcPI(this.t1.value);return false;">
Number of Digits:<br>
<input type="text" name="t1" id="t1" value="100" size="25" maxlength="25">
<input type="checkbox" name="cbCount" id="cbCount" value="" checked="checked">
<input type="checkbox" name="cbSpace" id="cbSpace" value="" checked="checked">
<br>
<input type="button" value="Calculate Pi" onclick="calcPI(this.form.t1.value)">
</form>
<div id="d1">0</div>
</body>
</html>
﻿```
I hope this code will be useful to you.
Thank you.

3. ## Re: [JAVASCRIPT] - Calculating Pi

Technically, the OP code is a Monte Carlo simulation that will generate a reasonable approximation of pi. But every time that code is ran, a slightly different result is likely to be returned.

And I'm only adding this note because this thread was needlessly bumped already.

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