What's New - June 2003
June 27, 2003: A replacement version of the Spring Mass 1 program was posted today. It's an animated demo program of a simple spring-mass system with user controlled parameters. Fellow Delphian Don Rowlett had spotted a bug or two and suggested some changes. I fixed the bug and added a couple of other features as a bonus. The exercise reminded me that I had planned a Spring Mass 2 program to handle multiple coupled springs and masses. It's back on the active list (which still may stretch into next winter).
June 13, 2003: Alert viewer Charles Doumar sent code to correct the "corner" problem with yesterday's Knight's Tour posting (specifying any corner for an end point results in long search times). I posted the revision today. It looks like the problem with "next to corner" end points remains though (any end point one knight move removed from a corner). Charles will be working on it this next week - and I'll be at the beach on vacation! (Well, I will have my laptop with me in case of rain <g>.) See you in a week.
June 12, 2003: A simple modification to the
Knight's Tour program was
posted today which allows users to specify an ending square as
well as a beginning square for program solution searches.
In most cases a procedure similar to that used for "closed
tour" searches will find a solution in a few hundred trial
moves. However, a test case starting at square (1,1)
and ending at square (8,1) was stopped after 10,000,000
trial moves, so there is obviously room for a smarter method!
June 11, 2003: An alert user recently spotted a bug in our Multi-Pile Nim program. In the "last token loses" version, the computer could lose if the human played well - but proudly announced: "Computer wins again!" after losing!. The replacement version posted today may still lose but now he at least admits it.
June 10, 2003: Here is #7 in the numeric t-shirt series. These hypothetical t-shirts are primarily programming exercises. The back of this shirt reads: "The only set of prime numbers containing all of the digits 1 through 9 and whose sum is a 3-digit number." And the front of the shirt reads:
See the answer and check out the code at T-Shirt #7.
June 8, 2003: Summertime things are not leaving much spare time for programming this month, but I do have a request. The other day, a viewer asked if I could design a a Knight's Tour that starts and ends on specific squares. I'm not aware of a specific algorithm for this,. but maybe one of our knowledgeable viewers does. If you can shed any light on this variation of the problem, please drop me a line. In the the meantime, I'm going to refresh my memory and take a look at our existing Knight's tour program to see if it can be easily modified to target a specific square as the final move.
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