A Quick Measure of Sortedness

How do you measure the "sortedness" of a list? There are several ways. In the literature this measure is called the "distance to monotonicity" or the "measure of disorder" depending on who you read. Here, I propose another measure for sortedness.

Rules for Effective C++

The rules for safe C++ code are surprisingly controversial.

Cross-domain communication the HTML5 way

Making a web application mashable -- useable in another web page -- has some challenges in the area of cross-domain communications. Here is how I solved those problems for Zwibbler.com, using HTML5 cross domain communication.

qb.js: An implementation of QBASIC in Javascript

Play NIBBLES.BAS in your browser. I re-implemented a small part of QBASIC as a compiler in Javascript, so it runs in a webpage.

Zwibbler: A simple drawing program using Javascript and Canvas

Now it's a commercial product, but Zwibbler was once a fun side-project, and here's some details on its implementation.

Experiments in making money online

Is it possible to make money on the internet, if you try really hard? I want to find out. I have always been interested in getting money for doing nothing.

Yes, You Absolutely Might Possibly Need an EIN to Sell Software to the US

After many months, your software sale is complete! You've got a purchase order, sent the invoice, delivered the software. You're already handling some support issues from users at BigCorp. Then BANG! Martha from Procurement emails back, as a favour, just to let you know that BigCorp has not received your W8 form with a valid tax id, and therefore will be withholding 30% of the purchase price of your multi-thousand dollar product for taxes.

Four ways of handling asynchronous operations in node.js

Javascript was not designed to do asynchronous operations easily. If it were, then writing asynchronous code would be as easy as writing blocking code. Instead, developers in node.js need to manage many levels of callbacks. Today, we will examine four different methods of performing the same task asynchronously, in node.js.

O(n) Delta Compression With a Suffix Array

The difference between two sequences A and B can be compactly stored using COPY/INSERT operations. The greedy algorithm for finding these operations relies on an efficient way of finding the longest matching part of A of any given position in B. This article describes how to use a suffix array to find the optimal sequence of operations in time proportional to the length of the input sequences. As a preprocessing step, we find and store the longest match in A for every position in B in two passes over the suffix array.

How to run a linux based home web server

Sometimes you need complete control over the server, and don't want to pay $20 to $40 a month for a VPS. In this article, I'll describe step by step how to set up a home web server using Ubuntu, capable of handling modest spikes in traffic.