Walking Randomly

When I first started this blog, there were only really two methods by which readers could keep up with new content – by subscribing to the RSS feed or by regularly dropping by the site to see what’s new. Since then readers have steadily been requesting other ways to follow the blog and, for the most part, I have obliged.  Here’s a list of current methods:

• Subscribe to the RSS feed – Join around 2500 others and subscribe to the WR RSS feed.  This number will probably be severely reduced once Google Reader shuts down.
• Follow me on Twitter – I post every WR article to my twitter feed along with whatever else I find interesting. Twitter is also a great way of contacting me and is the social media platform on which I am most active.
• WalkingRandomly on Google+ – I link to WR articles just after they are posted along with other random musings.
• WalkingRandomly on Facebook – A small following compared to the other channels but useful to some it seems.
• Drop by the site whenever the mood strikes you

I know it’s a day late but someone just sent me this and I simply had to share so please indulge me.  Solve this inequality to find the love

9x-7i>3(3x-7u)

One of the benefits of working at a university is that you are surrounded by a lot of smart people doing very interesting things and it usually doesn’t take much effort to get them to talk about their research.  I work in the faculty of Engineering and Physical Sciences which means that I’m pretty well covered in subjects such as mathematics, physics, chemistry, engineering, computer science, materials and earth sciences but I have to go all the way to the other side of campus if I want to learn a little about the life sciences.

Last week, I attended a free event called The Rogue Cell which was arranged by The Wellcome Trust Centre for Cell-Matrix Research and hosted by  The Manchester Museum as part of World Cancer Day.  I had no idea what to expect out of the evening but if you were to press me I would have guessed that there was going to be a lot of power point slides and row upon row of gently dozing delegates.  I could not have been more wrong.

The event was arranged in a workshop format where all of the attendees were split into five groups of six or so.  Each group was then assigned a Wellcome Trust Researcher who’s job it was to explain to us one of five defining characteristics of a cancer cell which were

• Evading the immune system
• Angiogenesis (formation of blood vessels)
• Migration/invasion
• Proliferation
• Lack of apoptosis (programmed cell death).

Each group kept their researcher for 20 minutes or so before they got assigned a new one who discussed a different topic from the five.  So, by the end of the evening we had covered the lot.  The presentations were intimate, informal and highly interactive and it felt to me like I was having a good chat down my local pub with a group of people who just happened to be world-class cancer researchers.  If only all learning experiences were like this one!

There was a great cross section of attendees from PhD biology students through to clinicians, undergraduates, random people off the street and, of course, the occasional math software geek.  One of the great things about this event was the fact that everyone seemed to get a lot out of it, no matter what their background.  I asked a lot of questions, many of which would have been blindingly obvious to a student of the life sciences but not once was I made to feel stupid or out of place.  It must have been exhausting for the presenters but I can honestly say that it was one of the most enjoyable learning experiences I’ve had for quite some time.

I sincerely hope that The Wellcome Trust Centre for Cell-Matrix Research and The Manchester Museum will be arranging more events like this in the future.

Links:

The following links were sent to us following the event.  I include them here for anyone who’s interested.

Evasion of Immune System:

• New cancer therapy:http://www.youtube.com/watch?v=t3bI9nBa4FY
• Herceptin mechanism of action:http://www.youtube.com/watch?v=IeE3K7U9fTQ

Migration/Invasion

• http://www.youtube.com/watch?v=JaqgovL51Cc

Proliferation

• http://www.cancerresearchuk.org/cancer-info/prod_consump/groups/cr_common/@nre/@car/@gen/documents/flash/018206.swf
• http://www.youtube.com/watch?v=IeUANxFVXKc&feature=related
• http://www.youtube.com/watch?v=Hm03rCUODqg&feature=related

Angiogenesis

• http://www.youtube.com/watch?v=mvsF_pIClaI

I am having a friendly argument with a colleague over how you calculate the peak number of floating operations per second (flops) for devices that support Fused Multiply Add (FMA).  The FMA operation is d=a+b*c, an operation that can be done in one cycle on devices that support it.

I say that an FMA operation is two flops, he says it’s one.  So, when I calculate the theoretical peak of a device I get twice the value he does.  So, what do you think..is FMA one flop or two?

I like the StackOverflow range of question and answer sites and have hopped on and off them almost since the very beginning.  When I logged in recently I was informed that one of my questions had been awarded the ‘Famous Question’ badge..i.e. it had been viewed over 10,000 times.  The relevant question was Python blogs that you regularly follow? which was asked by me in the very early days of the site. Not only has it received 63 community up-votes and over 10,000 views but it’s also been closed as ‘Not constructive’ by senior members of the Stack Overflow community.

I find this contrast amusing!

Someone recently asked me if WalkingRandomly.com had a facebook page.  Since it wasn’t much effort to create one, I have now done so.  I have no idea if this will be of any use to anyone but a first stab at it is at http://www.facebook.com/Walkingrandomly 

Now I have to decide what to do with it. Does anyone have any thoughts on a blog such as this having its own facebook profile?  Is it a good idea?  Will anyone make use of it or is it just pointless?

My first post on WalkingRandomly was on 20th August 2007 and, to be honest, I had no idea what I was going to write about or if I would keep at it; I certainly didn’t think that I would still be going strong 5 years later.  Although I love to write, there is one reason why I keep on pounding out the posts here…you!

To all commenters, twitter followers, emailers and anyone else who has contacted me over the last 5 years regarding this blog….THANK YOU!  Without you, I would have given up years ago because no one wants to write reams of stuff that doesn’t get read.

There are various things one could write about for a post like this.  Maybe I could post reader statistics for example or discuss what I’ve got out of blogging over the last few years.  Alternatively, I could go down the route of posting links to some of the posts I’m most proud of (or otherwise!).  I considered all these things but realised that what was most important to me was just to say thank you to all of you.

Thanks!

This little corner of the web that I like to call home has been online for 4 years as of today.  I’d like to thank everyone who reads and comments on the stuff I put up here, I hope you find my wanderings interesting and/or useful.

I’d also like to thank all of the people and organisations I have collaborated with over the years while writing articles here. I’m not going to mention names out of fear of missing someone out but you know who you are.  The only exception would be Matthew Haworth of Reason Digital who talked me into starting this up during his University of Manchester farewell party.  He also provides me with web hosting (surviving three slashdottings so far), technical support and, on occasion, lunch!  Without Matt, there would be no Walking Randomly.

Back on WRs first birthday I gave out some stats (143 RSS subscribers and 250 visits per day) and so I’ll so the same today (1645 RSS subscribers and 800 unique visits per day)

Finally, here is a list of some of my favourite articles from over the last 4 years.  I hope you enjoy reading them as much as I enjoyed writing them

• Secret Messages hidden inside equations – When an equation literally spoke to me.
• The Valentine’s equations – Hearts and flowers, wrapped up in equations
• Now thats what I CALL Retro Computing – Ever wondered how easy it would be to program a 60 year old computer?  Now’s your chance
• Simulating Harmonographs – Pretty pictures from pendulums
• Proof I have a brain – When I blagged my way to a free brain scan
• Should Fortran be taught to undergraduates? – My first Slashdotting.  This post has been read by tens of thousands of people.
• Wheels on Wheels on Wheels – More pretty patterns
• The unreasonable ineffectiveness of factoring – We drill and kill the technique of factoring equations in schools.  A pity that its useless then!
• Polygonal numbers on quadratic number spirals – Yet more pretty patterns
• Math on iPad #1 – The beginning of a series that is still ongoing
• Quadraflakes, Pentaflakes, Hexaflakes and more – Playing with a particular kind of Fractal
• Complex Power Towers – recreations in the complex plane

I’ve been a user of Ubuntu Linux for years but the recent emphasis on their new Unity interface has put me off somewhat.  I tried to like it but failed.  So, I figured that it was time for a switch to a different distribution.

I asked around on Twitter and got suggestions such as Slackware, Debian and Linux Mint.  I’ve used both Slackware and Debian in the past but, while they might be fine for servers or workstations, I prefer something more shiny for my personal laptop.

I could also have stuck with Ubuntu and simply installed GNOME using synaptic but I like to use the desktop that is officially supported by the distribution.

So, I went with Linux Mint.  It isn’t going well so far!

I had no DVDs in the house so I downloaded the CD version, burned it to a blank CD and rebooted only to be rewarded with

Can not mount /dev/loop0 (/cdrom/casper/filesystem.squashfs) on //filesystem.squashfs

I checked the md5sum of the .iso file and it was fine. I burned to a different CD and tried again. Same error.

I was in no mood for a trawl of the forums so I simply figured that maybe something was wrong with the CD version of the distribution – at least as far as my machine was concerned. So, I started downloading the DVD version and treated my greyhound to a walk to the local computer shop to buy a stack of DVDs.

When I got back I checked the .md5 sum of the DVD image, burned it to disk and…got the same error. A trawl of the forums suggests that many people have seen this error but no reliable solution has been found.

Not good for me or Linux Mint but at least Desmond (below) got an extra walk!

Update 1 I created a bootable USB memory stick from the DVD .iso to elimiate any problems with my burning software/hardware. Still get the same error message. MD5 checksum of the .iso file is what it should be:

md5sum ./linuxmint-11-gnome-dvd-64bit.iso
773b6cdfe44b91bc44448fa7b34bffa8  ./linuxmint-11-gnome-dvd-64bit.iso

My machine is a Dell XPS M1330 which has been running Ubuntu for almost 3 years.

Update 2: Seems that this bug is not confined to Mint. Ubuntu users are reporting it too. No fix yet though
https://bugs.launchpad.net/ubuntu/+bug/636711

Update 3: There is DEFINITELY nothing wrong with the installation media.  Both USB memory stick and DVD versions boot on my wife’s (much newer)HP laptop with no problem.  So, the issue seems to be related to my particular hardware.  This is like the good old days of Linux where installation was actually difficult.  Good times!

Update 4: After much mucking around I finally gave up on a direct install of Mint 11.  The installer is simply broken for certain hardware configurations as far as I can tell.  Installed Mint 10 from the same pen drive that failed for Mint 11 without a hitch.

Update 5: As soon as the Mint 10 install completed, I did an apt-get dist-upgrade to try to get to Mint 11 that way. The Mint developers recommend against doing dist-upgrades but I don’t seem to have a choice since the Mint 11 installer won’t work on my machine. After a few minutes I get this error

dpkg: error processing python2.7-minimal (--configure):
 subprocess installed post-installation script returned error exit status 3
Errors were encountered while processing:
 python2.7-minimal

This is mentioned in this bug report.  I get over that (by following the instructions in #9 of the bug report) and later get this error

p: cannot stat `/usr/lib/pango/1.6.0/module-files.d/libpango1.0-0.modules': No such file or directory
cp: cannot stat `/usr/lib/pango/1.6.0/modules/pango-basic-fc.so': No such file or directory
E: /usr/share/initramfs-tools/hooks/plymouth failed with return 1.
update-initramfs: failed for /boot/initrd.img-2.6.35-22-generic
dpkg: error processing initramfs-tools (--configure):
 subprocess installed post-installation script returned error exit status 1
Errors were encountered while processing:
 initramfs-tools

I fixed this with

sudo ln -s x86_64-linux-gnu/pango /usr/lib/pango

Trying the apt-get dist-upgrade again leads to

The following packages have unmet dependencies:
 python-couchdb : Breaks: desktopcouch (< 1.0) but 0.6.9b-0ubuntu1 is to be installed
 python-desktopcouch-records : Conflicts: desktopcouch (< 1.0.7-0ubuntu2) but 0.6.9b-0ubuntu1 is to be installed

Which, thanks to this forum post, I get rid of by doing

sudo dpkg --configure -a
sudo apt-get remove python-desktopcouch-records desktopcouch evolution-couchdb python-desktopcouch

A few more packages get installed before it stops again with the error message

Unpacking replacement xserver-xorg-video-tseng ...
Processing triggers for man-db ...
Processing triggers for ureadahead ...
Errors were encountered while processing:
 /var/cache/apt/archives/xserver-xorg-core_2%3a1.10.1-1ubuntu1.1_amd64.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)

I get past this by doing

sudo apt-get -f install

Then I try apt-get upgrade and apt-get dist-update again…possibly twice and I’m pretty much done it seems.

Update 6: On the train to work this morning I thought I’d boot into my shiny new Mint system. However I was faced with nothing but a blank screen.  I rebooted and removed quiet and splash from the grub options to allow me to see what was going on. The boot sequence was getting stuck on something like checking battery state. Up until now I had only been using Mint while connected to the Mains. Well, this was the final straw for me.  As soon as I got into work I shoved in a Ubuntu 11.04 live disk which installed in the time it took me to drink a cup of coffee. I’ve got GNOME running and am now happy. 

My Linux Mint adventure is over.

I love mathematics and I also love gadgets so you’d think that I’d be overjoyed to learn that there are a couple of new graphical calculators on the block.  You’d be wrong!

Late last year, Casio released the Prizm colour graphical calculator.  It costs $130 and its spec is pitiful:

• 216*384 pixel display with 65,536 colours
• 16Mb memory
• The CPU is a SuperH 3 running at 58Mhz (according to this site)

More recently, Texas Instruments countered with its color offering, the TI-NSpire CX CAS.  This one costs $162 (source) and its specs are also a bit on the weak side but quite a bit higher than the Casio.

• 320*240 pixels with 65,536 colours
• 100Mb memory
• CPU? I have no idea.  Can anyone help?

If you are into retro-computing then those specs might appeal to you but they leave me cold. They are slow with limited memory and the ‘high-resolution’ display is no such thing. For $100 dollars more than the NSpire CX CAS I could buy a netbook and fill it with cutting edge mathematical software such as Octave, Scilab, SAGE and so on.  I could also use it for web browsing,email and a thousand other things.

I (and many students) also have  mobile phones with hardware that leave these calculators in the dust.  Combined with software such as Spacetime or online services such as Wolfram Alpha, a mobile phone is infinitely more capable than these top of the line graphical calculators.

They also only ever seem to be used in schools and colleges.  I spend a lot of time working with engineers, scientists and mathematicians and I hardly ever see a calculator such as the Casio Prizm or TI NSpire on their desks.  They tend to have simple calculators for everyday use and will turn to a computer for anything more complicated such as plotting a graph or solving equations.

One argument I hear for using these calculators is ‘They are limited enough to use in exams.‘  Sounds sensible but then I get to thinking ‘Why are we teaching a generation of students to use crippled technology?‘ Why not go the whole hog and ban ALL technology in exams?  Alternatively, supply locked down computers for exams that limit the software used by students.  Surely we need experts in useful technology, not crippled technology?

So, I don’t get it.  Why do so many people advocate the use of these calculators?  They seem pointless!  Am I missing something?  Comments welcomed.

Update 1: I’ve been slashdotted!  Check out the slashdot article for more comments.

Update 2: My favourite web-comic, xkcd, covered this subject a while ago.

Other posts you may find useful / interesting

• Math on iPad #1
• Mathematics on the pocket PC