linux and windows tips, mathematics, and some recipes

Monday, August 27, 2007

How many Asian countries can you name?

Much more challenging than the 50 states quiz. If you think you know Asia, this site will really test you. Watch out for the former Soviet states and the territories of South East Asia.

read more | digg story

Monday, July 30, 2007

Name the 48 Counties of England

Continuing the venerable tradition of online geography quizzes, this page tests your knowledge of the 48 Ceremonial Counties of England. As you name the counties, the names are pinned to a map of England.

read more | digg story

Thursday, March 29, 2007

SIM card rejected? Phone doesn't ring?

I have a very basic mobile (cell) phone, bought simply to make and receive phone calls. After a year, I started getting the message "SIM card rejected" with increasing frequency, requiring me to restart the phone. Of most concern to me was that I might be missing calls during the periods of rejection. I took the phone (a Nokia 3120) to my local Orange shop where I was told that the phone might be dying on me and that I would have to get a new one. I was not pleased!

A few more months elapsed and I found that the phone had stopped ringing, though the vibrating alert continued to work. I checked my phone settings to make sure that it was set to ring. Everything seemed to be set up OK, and the phone was still producing bleeps, suggesting that the hardware was working properly. Again, I took the phone to the Orange shop and was told I'd have to buy a new phone. Given my belief that the hardware was operational, I decided not to give up on the phone. I turned to the user manual and found how to restore the factory settings. Having done this, my problems disappeared. Note that the contacts list and text messages stay intact after the restoration. If you have a similar phone, I've copied the instructions below:
Restore factory settings
To reset some of the menu settings to their original values, press Menu, and select Settings and Restore factory settings. Key in the security code and press OK. Note that the data you have keyed in or downloaded, for example, the names and phone numbers saved in the contacts list are not deleted.
More troubleshooting information is available from Nokia.

Tuesday, February 13, 2007

Amateur Mathematicians

Pierre de Fermat is the best known amateur mathematician, but the story of Grassman is much sadder. Something of a mathematical Van Gogh, he created the subject of linear algebra single-handedly, devised the first axiomatisation of arithmetic, and much else besides. His work was rejected by almost all professional mathematicians of the day, including Möbius and Kummer. Unlike Van Gogh, he didn't end up killing himself, but became a noted philologist instead!

Another case of a neglected mathematician is Kurt Heegner who solved Gauss' class number problem for imaginary quadratic fields (finding all nine such fields of class number 1). His proof was dismissed by the mathematical community until 1967 when Harold Stark developed a proof and showed it to be equivalent to Heegner's. Unfortunately, Heegner had died two years earlier.

Monday, July 24, 2006

How to log in to your Motorola WR850G wireless router


Dear Sir/Madam,

I can't access the control panel on my WR850G. I bought the unit in March and managed to set it up just fine. I enabled WPA-PSK and MAC-based authentication and disabled DHCP (as I was using another device as a router). I've had no problems with it since then, until just now when I bought a new laptop.

Naturally, I needed to access the control panel in order to enter the MAC address of my new wireless adapter. Unfortuately, nothing happens when I try accessing on my web browser (even using the machine which can get a wireless service from the router). I get a ping response from if I change my IP address to

I've tried resetting the router (by holding the reset button for 30 seconds while the power is on). This seems to have no effect and the router continues to transmit the old SSID.

I've also tried running the installation utility which came with the router. This works OK until it gets to the "detecting router" stage, and then stops.

Basically, I can use the router fine as a wired switch, and I can use it as a wireless access point with exactly one wireless adapter (the one whose MAC address I'd entered into the router using the control panel). I cannot access the control panel, hence cannot add the MAC address of my new laptop.

I would very much appreciate any help you can provide me with in solving this problem.


Hello Gihan
try this hook the router to the xp computer remove the modem from the router so just 1 eithernet cable going from one of the 4 lan ports on the back of the router and the other end to the back of the pc now go to start , then click on control panell
now click on internet and network connection then click on net work connection
or you may just see network connection now right click the local area connection and go and left click properties
now high light internet protocal tcp/ip and then click on properties
now put the dot in use the following ip address Then type each of the next but subnet mask should auto populate
subnet mask
default gateway=
Then click on ok then close
now open up internet exploror or mozilla and in the address bar type and see if you can get to the log in screen if you cant you will need to call the # below and talk to our tech support team there incase the router is faulty
let them know what we already did so they dont have to redo what weve already done
Thank you for chooseing motorola
If you need further assitant please respond to this email or contact us by 1877 466 8646
Thank you for choseing motorola you have a great day

Sunday, July 23, 2006

Using Xfig with LaTeX

Xfig is a program used to create drawings with lines, arcs, and splines. LaTeX is a document preparation tool. How do you use them together? I'll discuss a technique which allows you to use LaTeX strings within your figures (for mathematics, Greek text, etc). The first thing you'll need is the following entries in your LaTeX preamble:
The first package is essential for working with graphics in LaTeX, the second is needed because Xfig enters colouring commands into its LaTeX output (even if all the output is black). Fire up Xfig with the following options:
xfig -specialtext -latexfonts -startlatexFont default
If you don't want to do this every time, just add the following entries to your .Xresources file:
Fig.latexfonts: true
Fig.specialtext: true
Go ahead and make your figure. You can enter LaTeX strings as text, these will later be converted by LaTeX into beautiful mathematics.

When you're done with the figure, save it in the same directory as your LaTeX file, let's suppose you name the figure myfig.fig. Export the file as "Combined PS/LaTeX (both parts)". This will make two new files, myfig.pstex and myfig.pstex_t. When you need to use the file in your LaTeX document, enter something like:
\begin{figure} [ht]
\caption{My figure}
You might not be able to see the effects in the dvi file, but you should be able to see your figure if you run dvips mytexfile.dvi to create a PostScript file.

Working with PDFLaTeX

Similar principles apply if you want to end up with a pdf. Of course one simple solution is to run ps2pdf on your ps file from the previous section, but you may end up losing some pdf-specific features, such as hyperlinks. The recommended alternative is to run pdflatex instead of LaTeX. You'll need some changes to the preamble:
You use Xfig much as before, but this time you export the figure to "Combined PDF/LaTeX". This will produce files myfig.pdftex and myfig.pdftex_t. The latter file replaces myfile.pstex_t in the body of your LaTeX document. When using pdflatex, make sure that your Xfig is in the correct orientation (usually portrait).

Most of the information is this post was gleaned from the Xfig website, which contains much more information on using LaTeX with Xfig.

Saturday, July 15, 2006

Creating a Bootable Windows XP Setup CD

There are a number of reasons why you may need such a CD:
  • Your copy of Windows came preinstalled, and you'd like to have a backup in case something goes wrong.
  • You want a 'slipstreamed' setup disk, i.e. a setup disk which will install XP Service Pack 2 as part of a full install.
  • You want access to the Windows Recovery Console.
I actually fall into the last category — having decided to remove Debian Linux from my computer, I also wanted to remove its boot loader, GRUB, and replace it with the Windows boot loader. Unfortunately, this can only be done using the fixmbr program which comes with the Windows Recovery Console!

If you already have a Windows Setup CD, then all you need to do is to follow the instructions given in Paul Thurrott's web site. However, if you have a preinstalled version of Windows, you may find that the contents of the Setup CD are located somewhere on your hard drive. In my case, (with an Acer TravelMate 4151LMi) the Setup files are in C:\i386. You need to follow the instructions in Bart Lagerweij's web site to create a bootable CD from the Setup files.

If you have SP2 then you'll also need to 'slipstream' the Service Pack. Unless you already have the Service Pack file, you'll need to download it from Microsoft. Instructions for downloading and slipstreaming are given as Steps 2 and 3 in Paul Thurrott's web site (you need to modify the instructions a little to work with Bart's procedure).