Best of 2009

The blog posts Hacker News loved most in 2009. 58 posts.

Math & Algorithms
7

Step-by-Step Math

Have you ever given up working on a math problem because you couldn’t figure out the next step? Wolfram|Alpha can guide you step by step through the process of solving many mathematical problems, from solving a simple quadratic equation to taking the integral of a complex function.

11

Beautiful plots of roots of polynomials

Click on the picture for bigger view. Roots of quadratic polynomials are in grey; roots of cubics are in cyan; roots of quartics are in red and roots of quintics are in black. The horizontal axis of symmetry is the real axis; the vertical axis of symmetry is the imaginary axis. The big hole in the middle is centered…

14

The New Science of Causation

It seems like each new day brings another one of those headlines: regular sleep “linked to” life expectancy, playing video games “associated with” surgical prowess, bullies “at risk” of becoming criminals, and “does breastfeeding reduce a baby’s blood pressure?” (the old rhetorical question gambit). Sometimes the…

15

SciPy - the embarrassing way to code

I’ve programmed in many languages before, indeed I’ve spent at least a year working in Basic, C, C++, C#, java, assembler, modula-2, powerhouse and prolog. One thing I’ve never done before is Matlab, well except a few basic exercises for some course I did way back. A couple of years ago I started using python and more…

25

Functional Geometry

Peter Henderson wrote an article about a method to describe pictures with functional programs. I've implemented it in Lisp. An updated version of the article uses curves and different shapes and has some references to other applications for this method, like "An Algebra of Music".