Tuesday, April 29, 2014

More Climate Change

Lately, I've been reading a lot on anthropomorphic global warming (AGW), and trying to understand some of the legitimate skepticism directed at the consensus view.

Here is Steve Novella, tangentially talking about AGW. He summarizes my position more eloquently than I could, in talking about his own:
On many issues, however, there is a nuanced opinion somewhere in between the two extremes. I have no reason to doubt the scientific consensus on AGW, but we have to remember the current consensus is that AGW is 95% probable, meaning (if accurate) that one in 20 such statements will turn out to be wrong. Also, it is reasonable to question the efficacy of individual proposed solutions to AGW. I am still solidly in the “AGW is probably real and if we are going to do something about it we better start acting now,” camp, but I also don’t think we should white wash over current uncertainties in order to present a clean and united front. Science is messy and we have to deal with it.

Monday, April 28, 2014

Conceptual Mathematics

Grant Wiggins has a very interesting post on "conceptual mathematics".

The list of 9 misconceptions in arithmetic and the challenge test with 13 questions for conceptual understanding both make for very interesting reading.

The first misconception he cites:
1. A number with three digits is always bigger than one with two
. Some children will swear blind that 3.24 is bigger than 4.6 because it’s got more digits. Why? Because for the first few years of learning, they only came across whole numbers, where the ‘digits’ rule does work.

And the first question in the challenge test:
1) “You can’t divide by zero.” Explain why not, (even though, of course, you can multiply by zero.)
Very nice read. 

Sunday, April 27, 2014

Judith Curry and Climate Etc.

Judith Curry was a (relatively) recent guest on Russ Roberts' EconTalk. I found her blog "Climate etc." to be a refreshing voice on the climate science debate. It is informative, without being dogmatic.

In my opinion, a lot of scientists (I speak as one) often become overly defensive (for reasons I completely understand), when confronted by "climate skeptics"  (some of who are complete lunatics, but some who are legitimately skeptical about certain claims).

I think climate change is a serious issue, and that we should do something about it. However, I do believe we have to be pragmatic about it.

There was also a more recent EconTalk "episode" which addressed climate change. I think the tone of the debate was just perfect.

Monday, April 21, 2014

Cyclic Tridiagonal Matrices: Review

For reference, I wanted to collect recent posts which let us solve cyclic tridiagonal systems in one place:

(i) Why LU decomposition?
(ii) The Sherman-Morrison formula and LU decomposition, with an example.
(iii) The Thomas algorithm to solve tridiagonal systems
(iv) Finally cyclic tridiagonal systems, with some Fortran code

Friday, April 18, 2014

Weekend Links

1. The Foodbabe spews bullshit again! This time she targets ingredients in cookies that Doubletree hands out (I love them!). Steve Novella at Neuorologica blasts her arguments.
Her modus operandi is simple – look at ingredient lists for names that sound like chemicals or are difficult to pronounce, bypass any scientific analysis or evidence and go straight to hyperbolic fearmongering. Then just hope that companies cave in order to avoid negative press before anyone can ask too many questions.
2. This Quora thread on visually stunning math is simply awesome! Over the past few months I've found myself spending more time on Quora than on wikipedia.

3. Speaking of wikipedia, my opinion of Jimmy Wales went up by quite some, when he offered this no-apologies takedown of a petition on change.org, requesting wikipedia to be more open to "alternative" and holistic ideas. Here's what he said:
No, you have to be kidding me. Every single person who signed this petition needs to go back to check their premises and think harder about what it means to be honest, factual, truthful. 
Wikipedia's policies around this kind of thing are exactly spot-on and correct. If you can get your work published in respectable scientific journals - that is to say, if you can produce evidence through replicable scientific experiments, then Wikipedia will cover it appropriately. 
What we won't do is pretend that the work of lunatic charlatans is the equivalent of "true scientific discourse". It isn't.
Hats off.

4. These visualizations of the roots of polynomials are stunning! They are simply exquisite.

Thursday, April 10, 2014

The Story of Mona Lisa

I like listening to Michael Mauboussin talk about disentangling skill from luck. Here is a recent presentation from a keynote lecture.

If you have even a passing interest in statistics, you should listen to the entire talk; it is very enlightening.

At the 18:30 mark, he talks about "path-dependent" successes. When the audience is asked to name the most famous painting about 85% of the people say the "Mona Lisa". He goes on to discuss the reason why Mona Lisa became so famous, and the reason is truly interesting.

The Straight Dope has a fuller explanation on why Mona Lisa became famous.

Tuesday, April 8, 2014

Prisoner's Dilemma Game Show

You probably know all about the Prisoner's dilemma. If not, consider this wikipedia link.

Thanks to RadioLab, I found this amazing video:

Friday, April 4, 2014

Displaying Highlighted Code in LaTeX/Beamer

It is possible to produce "automatically" highlighted code in LaTeX/Beamer using the "lstlisting" package. It supports a wide variety of languages, and one can control color-schemes, treatment of columns, tabs etc.

To produce the following Octave code,

I used the following LaTeX code: