While studying from Larry Wasserman’s “All of Statistics”, I’ve found that the exposition of the Wald test was a little confusing to me, so that I struggled a bit in trying to derive a key result. Given that I didn’t find much on the internet to help me, and that I finally figured it out after a while, I thought of writing a small post for other confused students. Given a scalar parameter \(\theta\) of the distribution underlying the data, the Wald test uses its estimate \(\hat{\theta}\) to compute a statistic \({W}\), which is then used to pit a null hypothesis \({H}_0\) against an alternative hypothesis \({H}_1\). The distribution of the...

Read MoreWhile I’m going through the NLP course by Jurafsky and Manning on coursera, I coded a small python implementation of the Wagner-Fischer algorithm presented in lecture 6, 7 and 8. And here it is! Please refer to the lectures for a more in-depth explanations of the algorithm. I’ll just go quickly through the basics and then present the code. Introduction “How similar are these two strings?” Many people from different fields often end up asking themselves this question: the computational biologist comparing sequences of bases to see if they contain similar information; the computer scientist implementing speech recognition, trying to make sense of...

Read MoreFor the holidays, I made two resolutions: to fill my belly with quality food, and to fill my mind with quality thoughts. Both have been a success; the first one thanks to a girlfriend with a knack for cooking, the second one thanks to the local bookstore applying a very timely 20% off everything. Importantly, most of the quality thoughts that popped inside my holiday mind were brought about by one particular book. Sometime before Christmas, a friend pointed me to a great conversation between Sam Harris and Quantum Computation maven David Deutsch. Their discussion revolves on the ideas presented in the physicist’s book “The beginning of infinity”,...

Read MoreI’ll very soon be pleased to give a talk about my work on heteroclinic dynamics to other heteroclinic people with heteroclinic interests at the Heteroclinic dynamics in neuroscience workshop this December in Nice. In this heteroclinic setting, I thought it would be worth it to have a simple interactive simulation to play with while I illustrate my findings, as I don’t want the talk to be boring, and nothing boosts understanding like a good visualization! So I spent the last few days programming a simple visualizer in Python for the switching dynamics in the system described here, built upon the simulator I am using to produce the Terabyte of data needed for...

Read MoreLately I’ve been playing with org-drill, an extension to Emacs org-mode implementing a spaced repetition algorithm for flashcard drills. That is, org-drill lets you write flashcards in the form of org outlines plus special syntax, and have study sessions where the cards are presented to you using some special algorithms that should improve retention. The flashcards can have hidden text/images, present hints, have multiple faces, together with other useful settings. One of the main points of org-drill is of course its integration in org-mode, letting you keep your flashcards together with your other plain-text notes. The flashcards are no different from any...

Read MoreHi everyone, Lately I’ve been teaching an introductory course on the Theory of Computation at Plymouth University. The topic of my last lecture was the representation of real numbers in computers, and the unavoidable errors introduced by any choice of representation. Particularly, the lecture was focused on the floating point representation of real numbers. To make the nature of the float representation more intuitive to the students, I programmed a little visualizer which plots the numbers that can be represented with a floating point representation, given the number of bits in the exponential and in the mantissa. Within the visualizer, it is possible to change...

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