1267 search results for "latex"

Le Monde puzzle [#817]

April 18, 2013
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Le Monde puzzle [#817]

The weekly Le Monde puzzle is (again) a permutation problem that can be rephrased as follows: Find where denotes the set of permutations on {0,…,10} and is defined modulo 11 . Same question for and for This is rather straightforward to code if one adopts a brute-force approach:: (where I

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Math symbols in R charts: a cheat sheet

April 15, 2013
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Math symbols in R charts: a cheat sheet

If you're creating a scientific graphic in the R language, there's a good chance you'll be wanting to include some mathematical symbols somewhere on the chart. You might want to use a symbol like μ as an axis label, annotate a curve with simple math like x2, or even put a complete equation like: in the title. You can...

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Simulating the Gambler’s Ruin

April 14, 2013
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Simulating the Gambler’s Ruin

The gambler’s ruin problem is one where a player has a probability p of winning  and probability q of losing. For example let’s take a skill game where the player x can beat player y with probability 0.6 by getting closer to target. The game play begins with player x being allotted 5 points and player y allotted 10

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Checking the Goodness of Fit of the Poisson Distribution in R for Alpha Decay by Americium-241

Checking the Goodness of Fit of the Poisson Distribution in R for Alpha Decay by Americium-241

Introduction Today, I will discuss the alpha decay of americium-241 and use R to model the number of emissions from a real data set with the Poisson distribution.  I was especially intrigued in learning about the use of Am-241 in smoke detectors, and I will elaborate on this clever application.  I will then use the Pearson chi-squared

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knitr documents with tikzDevice graphics

April 13, 2013
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Setting up tikzDevice output in knitr may be a frustrating task, but gives outstandingly aesthetic, LaTeX-like figures. Here are my global knitr settings for typesetting documents in Polish (in UTF-8, make sure your R also runs in a Unicode locale…Read more ›

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Configure Kile for knitr under GNU/Linux

April 13, 2013
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Kile – a convenient LaTeX editor – may also be used to prepare knitr-generated reports. Here is how we may make our work much more efficient with a convenient compile-on-keypress feature. Create a bash script in your home directory, named…Read more ›

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Travis CI for R! (not yet)

April 12, 2013
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Travis CI for R! (not yet)

A few days ago I wrote about Travis CI, and was wondering if we could integrate the testing of R packages into this wonderful platform. A reader (Vincent Arel-Bundock) pointed out in the comments that Travis was running Ubuntu that allows you to install software packages at your will. I took a look at the documentation, and realized...

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Reserving with negative increments in triangles

April 11, 2013
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Reserving with negative increments in triangles

A few months ago, I did published a post on negative values in triangles, and how to deal with them, when using a Poisson regression (the post was published in French). The idea was to use a translation technique: Fit a model not on ‘s but on , for some , Use that model to make predictions, and then...

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High Obesity levels found among fat-tailed distributions

April 11, 2013
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High Obesity levels found among fat-tailed distributions

In my never ending quest to find the perfect measure of tail fatness, I ran across this recent paper by Cooke, Nieboer, and Misiewicz. They created a measure called the “Obesity index.” Here’s how it works: Step 1: Sample four times from a distribution. The sample points should be independent and identically distributed (did your

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Dirichlet Process, Infinite Mixture Models, and Clustering

April 7, 2013
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Dirichlet Process, Infinite Mixture Models, and Clustering

The Dirichlet process provides a very interesting approach to understand group assignments and models for clustering effects.   Often time we encounter the k-means approach.  However, it is necessary to have a fixed number of clusters.  Often we encounter situations where we don’t know how many fixed clusters we need.  Suppose we’re trying to identify

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