Merge Adobe PDF files

I was looking for a program that would merge Adobe PDF files.  At first I found this trial program, A-PDF Merger, which worked fine but left a small watermark on the first page.  Then I found this open source program, PDF Split and Merge, which did the trick but the UI is kind of slow, possibly because it is written in Java.  It looks like there are plenty of other free programs available too.

optional require in .emacs

In my .emacs I was loading the subversion plugin.

(require 'psvn)

Unfortunately on systems that don’t have the subversion plugin Emacs would barf on this line and stop loading the rest of the .emacs file.

Fortunately someone else had asked a similar question, alternative to (require …), on

Based on that thread I updated my .emacs with this code.

(condition-case nil
  (require 'psvn)
  (error (message "Subversion plugin unavailable, skipping load ...")))

Puzzle Interview Questions

  1. With a pencil and paper:
    1. Draw a large square
    2. Insrcribe a circle inside the large square
    3. Inscribe a small square inside the circle
    4. What is the ratio of the area of the large square to the area of the small square?

      Assume the width of the large square is d. The diameter of the circle inside the square is d and its radius is r = d/2.
      The small circle’s diagonal measures 2r. Therefore its area is 2r2. The large square’s area is d2 or 4r2.
      Therefore the ratio of the areas is 2:1.

  2. You wake up one morning to find an intact Boeing 747 in your front yard. You need to rent a crane to remove it. You need to determine the weight of the airplane in order to rent the correct crane. How do you figure out the weight of the airplane?

    I’d look it up on Google.
    But assuming I don’t have Google I’d guess like this:
    Plane can carry 500 passengers. Each passenger weighs 200 lbs plus about 100 lbs for a chair and 100 lbs for luggage and food. Let’s round up to 1000 lbs. That comes out to 500,000 lbs.
    Let’s assume the plane should be about 10 times heavier to carry such a load which is about the ratio between a car and a full passenger load.
    Therefore I will guess a Boeing 747 weighs between 5 and 10 million lbs.

  3. On a traditional analog clock, how many degrees separate the hour and minute hands at 3:15?

    Minute hand is at 90 degrees, where 3 is located.
    The hour hand is at the 3 plus 25% of the way to 4. There is 360/12 degrees between each numeral.
    Therefore the difference between the hour and minute 360/12/4 which is 7.5 degrees.

ThinkPad T60 Blank Display After Resume

Every once in awhile I’d find after leaving my Thinkpad for awhile that I’d find the screen blank. No matter what I did I could not get it to come back.

I finally figured out a workaround. By pressing Fn + Spacebar I decreased the screen resolution and the screen was displayed again. I then pressed Fn + Spacebar again to get back to my original display and then had to move back windows to where they were and resize some.

After doing this too many times I finally did a Google search to find out what was wrong. Fortunately this turned out to be a common problem, both on Windows and Linux.

Using the Windows Device Manager I saw that the driver for my ThinkPad PM (Power Management) Device was version According to this page the latest driver is

I updated this driver using ThinkVantage’s System Update utility (under Start Menu > ThinkVantage). I actually had to run the Software Installer which, because it was out of date, uninstalled itself and updated the System Update. Then when I ran the System Update it pulled down the driver update as part of its recommended updates.

So far the update seems to be working.

12/03/2007 – Turns out the update did not fix this problem. I then ran System Update and updated all critical and recommended updates. I am not sure if this solved the problem but I did notice my display now sometimes flickers. 🙁

Test Credit Card Numbers

Card Type Number
Master Card (16 Digits) 5105105105105100
Master Card (16 Digits) 5555555555554444
Visa (13 Digits) 4222222222222
Visa (16 Digits) 4111111111111111
Visa (16 Digits) 4012888888881881
American Express (15 Digits) 378282246310005
American Express (15 Digits) 371449635398431
Amex Corporate (15 Digits) 378734493671000
Dinners Club (14 Digits) 38520000023237
Dinners Club (14 Digits) 30569309025904
Discover (16 Digits) 6011111111111117
Discover (16 Digits) 6011000990139424
JCB (16 Digits) 3530111333300000
JCB (16 Digits) 3566002020360505

If you want more test credit card numbers try Google.

Problematic Adobe Photoshop Elements 4.0 Card Reader

Adobe Photoshop Elements 4.0 has a small utility called the Card Reader. Whenever you connect a camera USB or insert a card in a USB card reader the Card Reader pops up and allows you to download the photos onto your local hard drive and be added to the Photoshop Elements catalog.

However unlike with previous versions this Card Reader has proved to be problematic. It does not respond properly to the Windows close event so you have to manually close it when you are hibernating or logging off or shutting down.

Also the Card Reader for reasons unclear to me prevents certain applications from installing. Again the only way to get around this problem is to close the Card Reader.

In the end the convenience of the Card Reader was not worth the problems so I turned it off. It’s my impression as well as many others (see the reviews for 4.0 and 5.0 on that Adobe is continually degrading the quality and functionality of the Photoshop Elements product in every subsequent version.