Friday, August 20, 2010

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:
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.

    Thursday, August 12, 2010

    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:

    => "0A"
    => "2D"


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

    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 '() '())
    > (product '(1 2) '(1 2 3))
    ((1 1) (1 2) (1 3) (2 1) (2 2) (2 3))

    (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)