05 Oct 20
22 Sep 18
Article that describes the steps to generate the code in MS Excelwithout using any Visual Basic or other scripting.
30 Aug 17
Overview of several approaches to rank results by an average score provided by users, and why most fail to provide a satisfying solution. Concluding with a formula that yields better results.
10 Aug 16
06 Mar 12
List of ingenious algorithms in computer science
19 Jan 12
Efficiently querying geospatial data is a considerable challenge: because the data is two-dimensional (or sometimes, more), you can’t use standard indexing techniques to query on position. Spatial indexes solve this through a variety of techniques. This post covers several - quadtrees, geohashes, and space-filling curves - and reveal how they’re all interrelated.
29 Nov 11
Notes on the following algorithms and methods:
- Levenshtein distance
- Damerau-Levenshtein distance
- Bitap algorithm with modifications by Wu and Manber
- Spell-checker method
- N-gram method
- Signature hashing method
Introduction to Ternary Search Tries
02 Sep 11
Most people use this web site to get information about a particular number sequence. If you are a new visitor, then you might ask the database if it can recognize your favorite sequence, if you have one.
12 May 11
Encoding images under 140 characters.
05 May 11
If you have a web site with a search function, you will rapidly realize that most mortals are terrible typists. Many searches contain mispelled words, and users will expect these searches to magically work. This magic is often done using levenshtein distance. In this article, I’ll compare two ways of finding the closest matching word in a large dictionary.
13 Oct 10
Animation of the AES algorithm.
27 Aug 10
06 Aug 10
The purpose of this note is to illustrate how the ordinary standards of ran- domness have little to do with the type of randomness required for cryptographic purposes. That is, there are really two standards of randomness.
03 Aug 10
02 Jul 10
“When approaching the string comparison optimization problem, what we would like to do is to provide effective and efficient ways to rule out most of the candidate strings. We may refer to it as a “disqualifying comparison” - it lets us move faster down the search tree or move faster along the hash bucket linked list, until reaching the final string comparison in the search, keeping in mind that even the most efficient hash structure would probably waste a substantial amount of its time and cycles in string comparison.”
Shazam implemented in Java. It isn’t that hard !
25 Jun 10
That’s the crazy thing about malloc implementations. They all claim to be awesome in every way. So the burning question is: is this better than what I’m using today? I don’t know, but I’d sure like to!
15 Mar 10
Most credit card numbers are validated using an algorithm called the “Luhn check”. This is a very simple algorithm that doubles the odd digits and does a sum to see if the number is divisible by 10.
27 Jan 10
A new algorithm is proposed for removing large objects from digital images. The challenge is to fill in the hole that is left behind in a visually plausible way. A. Criminisi*, P. P´erez and K. Toyama