## Archive for December, 2010

This is the second post in a series. The third post is at http://www.walkingrandomly.com/?p=3512

### DataAnalysis – free curve fitting on iPad

DataAnalysis is a fantastic curve fitting and plotting package written by Evan Kantrowitz. You can import your data (in .csv format) from a variety of sources including email, iTunes and Dropbox. Once imported, DataAnalysis allows you to modify your data if necessary and then plot it in a variety of styles before fitting it to one of several different regression models.

There is a nice range of built in model types including polynomial (currently only up to order 3), power, exponential, gaussian and more with the full list detailed over at the DataAnalysis website. New model-types are being added all the time and the developer is willing to consider specific requests. Fitting is performed in the least-squares sense and the user can choose which numerical algorithm to use – Newton or Levenberg-Marquardt. My only gripe here is that it is not possible to define your own fit function so if the model you want to fit your data to has not been included then you are stuck.

Once you have completed plotting and fitting your data, you can export the whole thing in either .png or .pdf format via email, Dropbox or to the iPad Photos app. Alternatively, you can copy the graph to the iPad clipboard for inclusion in other apps.

This is a fantastic app that delivers exactly what it promises at a price that’s impossible to beat.

Back in May 2009, just after Wolfram Alpha was released, I had a look to see which fractals had been implemented. Even at that very early stage there were a lot of very nice fractals that Wolfram Alpha could generate but I managed to come up with a list of fractals that Wolfram Alpha appeared to know about but couldn’t actually render.

On a whim I recently revisited that list and am very pleased to note that every single one of them has now been fully implemented! Very nice.

Can you find any Wolfram Alpha fractals that I missed in the original post?

When I was 4 or 5 years old, my father taught me a lot of basic mathematics by exploiting my obsession with my grandmother’s collection of antiquated coins which I played with every chance I got. I loved the weird and wonderful collection of shapes and denominations that made up old English money; thruppenny bits, florins, shillings, ha’pennys, crowns, guineas…..there seemed to be no end to the variety and I loved them all. I was most definitely a noomtist which was the best rendition my young self could give of the word ‘numismatist’.

A farthing is an old English coin that was worth a quarter of a penny and Gran had lots of them. Dad would ask me things like **“I’ve got a halfpenny and a farthing, if I changed the lot to farthings then how many would I have?” **and **“How many farthings are there in a sixpence”**. Initially I would answer these questions by physically counting the coins. For example, I knew that there were 4 farthings in a penny so I would make 6 stacks of 4 and then count them, one by one, to get the answer: 1,2,3,4,5……21,22,23,24

This became laborious so at some point I’d answer similar questions by ‘counting in 4s’: 4,8,12…. and so on. Eventually, I didn’t need to count – I just knew that 6 stacks of 4 was 24 and so I had been tricked into learning my 4 times table before I had even started school. Dad, for his part, hadn’t delivered a single maths lesson – he just spent a few hours playing shopkeeper with his son.

Later, dad told me that there was such a thing as a third-farthing (1/12 of a penny) but Gran didn’t have any. If she did though, and he had 2 of them along with a farthing and a half-penny coin then how much money would he have? Questions such as this taught me about the arithmetic of fractions with no mention of the words ‘common denominator’ in sight. Good job too because, back then, I doubt I would have been able to pronounce ‘denominator’.

In fact it would be more accurate to say that I ‘discovered how to add fractions’ – my wily old dad didn’t teach me a thing – he just asked me questions about the fascinating little shiny things while we played games together.

A couple of years ago I wrote an article called Christmas gifts for math geeks and it has proven to be quite popular so I decided to write a follow up. As I started thinking about what I might include, however, I started to realise that I had produced a list for science geeks instead. So, here it is – my recommendations for gifts for the scientist in your life.

**Mathematica 8 Home Edition** – This is the full version of Mathematica, possibly my favourite piece of mathematical computer software, at the extremely low price of 195 pounds + VAT. I know what you are thinking ‘Over 200 quid is ** not** an extremely low price.’ and I would tend to agree. It is, however, very good value since a commercial license costs several thousand pounds and Mathematica is as good as MATLAB with a whole slew of toolboxes. Mathematica is possibly the most feature complete piece of mathematical software available today and is infinitely better than any dedicated graphical calculator.

**Bigtrak** – I don’t have a Bigtrak but I * used *to have one back in the 1980s. Is the science geek in your life into computers and 30-40 years old? If so then there is a distinct possibility that their first foray into the world of computer programming was with a Bigtrak back when they were 8 or so – I mean, this thing can even do loops! This isn’t identical to the original but it is a very close facsimile and would be great for budding computer nerds or their misty eyed old dad.

**200-in-1 electronic project lab**. Now this one brings back fond memories for me since it was given to me for my 10th birthday and is probably the reason I studied physics at A-Level since A-Level physics included the study of basic electronics. I did well in A-Level physics and enjoyed it so I chose theoretical physics for my degree later moving on to a PhD so you could argue that this piece of kit changed my life!

I was overjoyed when I discovered that it was still being sold and was immensely pleased when I received it as a birthday present once again when I was 28.

The first thing you need to know about this wonderful piece of kit is that it requires **no soldering**; you wire up all of the components using bendy little springs – nothing could be more simple. There is also no need to be able to read schematic diagrams (although this can be a great way to learn how to) since each spring is numbered so producing your own AM radio transmitter can be as simple as joining spring 1 to spring 10 to spring 53 and so on.

The practical upshot of all of this is that you can approach this thing at a variety of levels. In the first instance you can just have fun building and playing with the various circuits which include things like a crystal set radio, a Morse code transmitter, a light detector, a sound detector and basic electronic games. Once you’ve got that out of your system you can start to learn the basics of electronics if you wish.

I have since discovered 300 in 1 and even 500 in 1 electronic project labs which look great and all but this is the one that will forever be in my heart.

**Wonders of the Solar System** – I have always loved (although never practised) astronomy and avidly followed the adventures of Voyagers 1 and 2 when I was small. Since then, modern space probes such as Cassini-Huygens, Galileo and Mars Odyssey have added more to our knowledge of our astronomical backyard and we now know a tremendous amount about the solar system. In this series, Brian Cox of the University of Manchester takes us on a grand-tour around the solar system. The imagery is fantastic, Cox’s enthusiasm is infectious and the science is awesome. Yep, I quite like this DVD :)

**2011 ‘****Lightning Calculation’ calendar** – Ron Doerfler writes a blog called Dead Reckonings that specialises in the lost arts of the mathematical sciences. Last year he designed a 2010 Graphical Computing calendar and made the designs available for free to allow you to print your own. Centred around ancient computing devices called nomograms, the calendar was beautiful and after Ron very kindly sent me a copy, I encouraged him to make a version that he could sell. Well, I guess he took my advice because Ron is back with a 2011 calendar with the theme of ‘Lightning Calculations’ and this time he is selling it from Lulu.com.

Since Ron is an all round nice guy, he also offers a high resolution pdf of the calendar to allow you to print it off yourself but personally I plan on showing my support by putting an order in with Lulu.com. Nice work Ron!