The first two consecutive numbers to have two distinct prime factors are: 14 = 2 × 7 Read More: 278 Words Totally

The first two consecutive numbers to have two distinct prime factors are: 14 = 2 × 7 Read More: 278 Words Totally

Pentagonal numbers are generated by the formula, Pn=n(3n−1)/2. The first ten pentagonal numbers are: 1, 5, 12, 22, 35, 51, 70, 92, 117, 145, ... Read More: 472 Words Totally

What drives the estimates apart? Previously A post by Investment Performance Guy prompted “Variability of volatility estimates from daily data”. In my comments to the original post I suggested that using daily data to estimate volatility would be equivalent to using monthly data except with less variability. Dave, the Investment Performance Guy, proposed the exquisitely … Continue reading...

Timezone stuff can really drive you NUTS - at least if you’re sitting in front of a German Windows-Box This is what I used to do to set my tz: And I always wondered why R would throw “unknown timezone” warnings: Someday I found out that setting tz via `options()` was not enough as the … Continue reading...

We shall say that an n-digit number is pandigital if it makes use of all the digits 1 to n exactly once; for example, the 5-digit number, 15234, is 1 through 5 pandigital. The product 7254 is unusual, as the identity, 39 × 186 = 7254, containing multiplicand, multiplier, and product is 1 through...

In England the currency is made up of pound, £, and pence, p, and there are eight coins in general circulation: 1p, 2p, 5p, 10p, 20p, 50p, £1 (100p) and £2 (200p). Read More: 299 Words Totally

The number, 1406357289, is a 0 to 9 pandigital number because it is made up of each of the digits 0 to 9 in some order, but it also has a rather interesting sub-string divisibility property. Let d1 be the 1st digit, d2 be the 2nd digit, and so on. In this way, we note the...

Erkan Buzbas sent me an email about his webpage (operated as a wordpress blog) on ABC. It contains different items of information on ABC research and an hopefully growing list of references. After Scott Sisson’s tweet on ABC_research (latest news: two ABC sessions in ISBA 20122, Kyoto), here comes another way to keep posted about

Revolution R Enterprise 5.0 will be released soon, and Sue Ranney, VP of Development at Revolution Analytics, will host a webinar on Thursday November 17 to get you up to speed on the latest features: Revolution R Enterprise 5.0 is Revolution Analytics’ scalable analytics platform. At its core is Revolution Analytics’ enhanced Distribution of R, the world’s most widely-used...

Google slightly changed the html code it uses for hyperlinks on search pages last Thursday, thus causing one of my scripts to stop working. Thankfully, this is easily solved in R thanks to the XML package and the power and simplicity of XPath expressions: Lovely jubbly! P.S. I know that there is an API of

Following up from my previous post “Code Optimisation: One R Problem, Ten Solutions – Now Eleven!” I figured out a twelfth solution after writing that blog post. Furthermore, half way through writing this blog post I figured out a thirteenth solution too. As a recap, the problem is taken from rwiki where the goal is to find

We shall say that an n-digit number is pandigital if it makes use of all the digits 1 to n exactly once. For example, 2143 is a 4-digit pandigital and is also prime. What is the largest n-digit pandigital prime that exists? Read More: 288 Words Totally

Yes, yet another Bayesian textbook: Ioannis Ntzoufras’ Bayesian modeling using WinBUGS was published in 2009 and it got an honourable mention at the 2009 PROSE Award. (Nice acronym for a book award! All the mathematics books awarded that year were actually statistics books.) Bayesian modeling using WinBUGS is rather similar to the more recent Bayesian

The Seattle R User Group was kind enough to invite me to give a talk about R, C++ and Rcpp. So if you can make it to the Thomas building of the Fred Hutchinson Cancer Research Center in Seattle, WA, on December 7, I would love to see you there. I ha...

In response to my post about colour wheels, I received a suggested enhancement from Drew. The idea is to first match colours based on the text provided and then add nearby colours. This can be done by ordering colours in terms of hue, saturation, and value. The result is a significant improvement and it will capture all of

The simplest type of data object in R is a vector, which is simply an ordered set of values. Some further examples of creating vectors are shown below: Input: 1:20 Output: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 This creates...

As stated in CloudStat Intro, we know that CloudStat is based on R Language, an object orientated language, everything in R is an object. Each object has a class. The simplest data objects are one-dimensional arrays called vectors, consisting of any nu...

Reading our local weekly press this evening (the Isle of Wight County Press), I noticed a page 5 headline declaring “Alarm over death rates at St Mary’s”, St Mary’s being the local general hospital. It seems a Department of Health report on hospital mortality rates came out earlier this week, and the Island’s hospital, it

I came across an ingenious simulation by Perron during my Time-series lecture which I thought was worth sharing. The idea was to put your model to a further test of breaking trend before accepting the null of unit root. Let me try and illustrate this in simple language. A non-stationary time series is one that has its mean changing...

In a previous post, I discussed how to generate PPC keywords in R. In this post I will provide another example of how to perform this task. Let’s say that I am a auto insurance company that only operates in the state of Illinois. I’m planing on bidding on keywords in Bing and Google which

The good folks at DataMarket have posted a new tutorial on using the rdatamarket package (covered here in August) to easily download public data sets into R for analysis. The tutorial describes how to install the rdatamarket package, how to extract metadata for data sets, and how to download the data themselves into R. The tutorial also illustrates a...

match and %in% are two very commonly-used function in R. So, what's the difference of them?First, how to use them -- (copy from R manual)match returns a vector of the positions of (first) matches of its first argument in its second.%in% is a ...