Web Worker Script for "Calculating Pi in a Web Worker"

index.html

This is the Web Worker for<br/>&quot;Calculating Pi in a Web Worker&quot;.

<!-- To see more, go here: http://codepen.io/AndrewBarfield/pen/VYKwJO -->

script.js

/*

This script was adapted from Ken Ward's Java Script Tutorial located at:
http://www.trans4mind.com/personal_development/JavaScript/longnumPiMachin.htm

*/


mess = "";
Base = Math.pow(10, 11);
cellSize = Math.floor(Math.log(Base) / Math.LN10);

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);
        Add(n, aX, aAngle);
        while (!isEmpty(aAngle)) {
            Div(n, aAngle, iAng_squared, aAngle);
            Div(n, aAngle, k, aDivK);
            if (sign)
                Add(n, aX, aDivK);
            else Sub(n, aX, aDivK);
            k += 2;
            sign = 1 - sign;
        }
        mess += "aArctan=" + aArctan + "<br>";
    }
    // Calculate pi
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);
    makeArray(arrayLength, aDivK, 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);
    }
    //we have calculated pi/4, so need to finally multiply
    Mul(arrayLength, aPI, 4);
    //we have now calculated PI, and need to format the answer
    //to print it out
    sPI = "";
    tempPI = "";
    //put the figures in the array into the string 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) + ".";
        else {
            if ((i) % 50 == 0 && i != 0)
                sPI += tempPI.charAt(i);
            else
            if (i % 5 == 0)
                sPI += tempPI.charAt(i);
            else
                sPI += tempPI.charAt(i);
        }
    }
    ans += (sPI);
    t2 = new Date();
    return ans;
}

self.onmessage = function(e) {
    self.postMessage(calcPI(5000));
};

style.css

/* latin */
@font-face {
  font-family: 'Roboto';
  font-style: normal;
  font-weight: 400;
  src: local('Roboto Regular'), local('Roboto-Regular'), url(http://fonts.gstatic.com/s/roboto/v14/fg2nPs59wPnJ0blURyMU3PesZW2xOQ-xsNqO47m55DA.woff2) format('woff2');
  unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02C6, U+02DA, U+02DC, U+2000-206F, U+2074, U+20AC, U+2212, U+2215, U+E0FF, U+EFFD, U+F000;
}

body {
  margin: 20px;
  font: 60px/60px 'Roboto', sans-serif;
  color:#fff;
  background-color: #593f6b;
}

Web-Worker-Script-for-"Calculating-Pi-in-a-Web-Worker".markdown

Web Worker Script for "Calculating Pi in a Web Worker"

A Pen by Andrew Mitchell Barfield on CodePen.

License.