Posts Tagged ‘ Technical ’

The Automatic Millionaire & Amortization

January 8, 2011
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The Automatic Millionaire & Amortization

Dan Byrne of Vanderbilt University gave me a book back in October titled The Automatic Millionaire by David Bach. The book is an easy read and full of sound advice that I intend to take. Bach espouses a plan for retirement built on the principles of “paying yourself first” (i.e. before taxation, 401(k), 403(b)), making

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Bayesian Diabetes Projections by CDC

October 22, 2010
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Bayesian Diabetes Projections by CDC

Bayesian methods are supporting decisions and news at the national level! The Centers for Disease Control and Prevention summarizes a report published in the journal Population Health Metrics. The news also made it to the national media. The report (JP Boyle, TJ Thompson, EW Gregg, LE Barker, and DF Williamson (2010) “Projection of the year

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A Not Quite Random Number Generator (NQRNG)

September 13, 2010
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A Not Quite Random Number Generator (NQRNG)

I connected the instrumentation amplifier described in an earlier post to a piezoelectric transducer (buzzer) and made recordings at 5000 gain. The plot below shows 1000 such measurements over 1.0 seconds. There is a 4.0 second (at 1000Hz) sample of the data here piezo.csv. There is a clear sinusoidal signal in these data of about

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ECG Project

September 8, 2010
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ECG Project

In an earlier post, I described some ECG signal processing. In fact, these recordings were from my own heart, and I had collected them using a homemade ECG. The following is a repost from my old site describing the device. I assembled an instrumentation amplifier to measure cardiac potentials (i.e. an electrocardiograph (ECG)). The analog-to-digital

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Eigenimages: The AT&T Cambridge Faces Database

September 7, 2010
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Eigenimages: The AT&T Cambridge Faces Database

I picked up the AT&T Laboratories Cambridge database of faces for a clustering application. The database consists of images of 40 distinct subjects, each in 10 different facial positions and expressions. Typically, the goal of clustering in these data is to recover the ‘true’ partition, or that which isolates images of distinct subjects. Each image

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Tools for Hacking R: Git + Subversion

August 24, 2010
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In an earlier post, I discussed how to use Subversion to download, edit, and generate a patch against R‘s source code. Since most of us can’t commit our code changes back to R‘s repository, we can consider alternatives to store and maintain our patch, until it is eventually incorporated into R. Of course, our changes

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Tools for Hacking R: Subversion

August 23, 2010
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The development version of R is stored in a Subversion repository at the URL http://svn.r-project.org/R/trunk/. In fact, you can browse the source code by clicking the link. Subversion Hierarchy Subversion is software for source code revision control. That means it keeps track of changes, who made them, when they were made, and any comments about

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R Environments for Gibbs Sampler State

August 10, 2010
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R Environments for Gibbs Sampler State

I recently decided to revisit some R code that implements a Gibbs sampler in an attempt to decrease the iteration time. My strategy was to implement the sampler state as an R environment rather than a list. The rationale was that passing an environment to and from functions would reduce the amount of duplication (memory

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Extension to an R Package: brew gets a weave

July 28, 2010
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I’ve had enough of copy and pasting output from my R session into my email editor, blog, etc. I need something like Sweave for plain text files. In particular, I want the result of parsing <<echo=TRUE>>= f <- function(x) { x + 1 } f(1) @ with Sweave, but without the latex markup. For example,

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A tty Connection for R

July 26, 2010
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I completed (some time ago) an initial version of a patch for R, version 2.11.1, that adds a POSIX tty connection. The patch is confirmed to compile and works on Mac OS X (thanks to Ashwin Bhat of Georgia Tech) and Debian GNU Linux. However, it should be portable to other POSIX compliant operating systems.

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