Suppose you want to select k things randomly from a list of n items, with no duplicates. Of course, if k > n, then it's hopeless, and if k = n it's trivial, so the interesting case is when k < n. A naive approach might pick an item randomly, and try again …
Posted Fri 27 June 2008 by mcherm in Math, Programming
In a previous article I talked about using salt with a secure hash, but all of the examples assumed that the secure hash would be used to validate passwords. Secure hashes can be used for many other purposes, and I'll illustrate that by describing two other possible uses.
The first …
Posted Thu 12 June 2008 by mcherm in Programming
Any software project needs a Business Requirements Document (BRD)—a document which describes what the deliverable is supposed to do once it's been built. The traditional (waterfall) way is to write it in paragraph form, but several agile development techniques recommend writing it in the form of a collection of …
Posted Mon 12 May 2008 by mcherm in Programming
I'm not a very good cook. One reasons is that I've never mastered the art of tasting the food as I go along and seasoning it properly. When cooking, I never seem to add the right amount of salt. As a programmer, though, I always use salt.
"Salt", in programming …
Posted Mon 05 May 2008 by mcherm in Programming
Edward Lorenz died this past Thursday at age 90. This is as good an excuse as I will ever have to recount the story of his discovery (which I first learned from the book Chaos by James Gleick). It is a tale of math and the proper use of computers …