Installing the MySQL RubyGem on Ubuntu

I have successfully installed the MySQL driver for Ruby on Windows and Mac OS X but I had not installed it on Ubuntu until today.

I am assuming that you have already installed the MySQL server.  I am using MySQL 5.1.
$ sudo apt-get install mysql-server

Install the MySQL database client library.  I am not certain of this but I believe that the number '15' in 'libmysqlclient15-dev' indicates the version.  This is apparently the most current one and the default version on Ubuntu 10.4 as of today.
$ sudo apt-get install libmysqlclient15-dev

Install RubyGems if you have not done so already.  I am using Ruby 1.9.1.
 $ sudo apt-get install rubygems1.9

If everything was successfuly, then you should be able to use the mysql RubyGem in  your Ruby scripts.

Installing Windows 7 Professional on HP Pavilion tx2000

Yesterday, I did a clean install of Windows 7 (32-bit) on my HP Pavilion tx2000 computer. I was very surprised and glad that I did not need to install much in order to get the computer to work.  I feared that I would need to install many more drivers, for instance, the tablet driver.

Additional drivers installed from the HP support website:

• Realtek High Definition Audio
• Enables the mute button to change color to red when volume is muted.
• Source: http://h10025.www1.hp.com/ewfrf/wc/softwareDownloadIndex?softwareitem=ob-75992-4&lc=en&dlc=en&cc=us&os=4062&product=3744020&sw_lang=
• HP Quick Launch Buttons
• Enables most of the quick launch buttons on the screen border
• rotate, settings, media (prev, play, next, stop)
• Auto-rotates screen when you convert the laptop to a tablet
• Source: http://h10025.www1.hp.com/ewfrf/wc/softwareDownloadIndex?softwareitem=ob-78740-1&lc=en&dlc=en&cc=us&product=3744020&sw_lang=&os=4062

Things that do not work:

• DVD Quick Play button on the border of the screen
• I am not going to fix this.  I thought it was annoying anyways.  I kept on pressing it accidentally.

Observed benefits over the HP factory installation of Windows Vista.

• Startup time is now 57 seconds.
• From being powered off to displaying the google homepage.
• Shutdown time is now 10 seconds
• With Vista it would literally get too hot for your lap.  Now it always stays cool.  I would dare to say that it stays cooler than my 13" Macbook.

I hope this helps somebody somehow.

Formatting Hex Strings in Ruby

This method converts a 1 or 2 character string representing a hex number into a 2 character string representing a hex number.

Usage examples:

irb(main):001:0>format("a")
=> "0A"
irb(main):002:0>format("2D")
=> "2D"


Implementation:

def format_hex_string(byte)
    byte.upcase
    byte.to_i(16) >= 16 ? byte : "0" + byte
end


Cartesian Product in Lisp

One of the things I do quite often is calculate the Cartesian product of two lists.  Here is my solution to problem in Lisp.

Usage Example:
> (product '() '())
NIL
> (product '(1 2) '(1 2 3))
((1 1) (1 2) (1 3) (2 1) (2 2) (2 3))


Implementation:

(defun product (list1 list2)
    (let (templist '())
        ;;iterate through the first list
        (dolist (item1 list1)
            ;;iterate through the second list
            (dolist (item2 list2)
                ;;create a list from the current items and push it onto the temporary list;;
                (push (list item1 item2) templist)
            )
        )
        ;;reverse the temporary list to display it correctly
        (nreverse templist)
    )
)