# What's New -  January 2003

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January 30, 2003:  Viewer Zebulon has been working hard, and with some success, at finding bugs in the Tangram2 program.   In more complex tangrams, pieces sometimes could not be dropped  where they should obviously fit.  In the original version, for example, you cannot drop the parallelogram in the position shown in this figure from tangram file medium.tan.   Placing it there will not help solve the puzzle, and  pieces would always drop in their "correct" positions, but there's no logical reason that the piece should not drop in this location  -   now it will.   (For the curious, the drop failed if piece being dropped  shared a  single point with a non-vertex border point of a solution piece.)  The version posted today  isn't perfect yet, but it  is an improvement over  the original.

January 23, 2003:    Andy Womack sent me a note with a new shorter solution to the Rally marble puzzle1 X Horizontal-Clockwise, 4 X Vertical-Counterclockwise, and 3 X Horizontal -Clockwise will replace the red marbles with blues in 8 single position moves.  My previous best had been 9.  Surely 8 is the minimum?.

January 22, 2003:  10 Easy Pieces is a set of the first ten even numbered programs from the Euler Project programming challenge at educational site  mathschallenge.net.      If you want to take the challenge, I suggest you go there, sign up, and work on the problems first.  If you just want to see how 20 or 30 lines of Delphi code can  solve problems like

• the sum of all prime numbers up to 1,000,000.

• the sum of the digits in the expansion of 100 factorial.

• the largest palindrome that can be formed formed as the product of two 3-digit numbers.

January 20, 2003: Albrecht Durer (actually Dürer) created the Durer Magic Square  as one element of a copperplate engraving in 1514.  (Notice the date in the bottom row.)    I used it as the base to enumerate all 86 solutions in this program which also lets you try to find solutions yourself.  It's surprisingly hard - I have never managed to find even half.   By the way, astute viewers will note that the same 86 solutions exist for any 4X4 magic square containing the numbers 1 through 16.   Now whether this one has the most symmetric solutions is an interesting question that someone may have answered - but not  this programmer.

January 18, 2003:  Big Combos  is a program that will display very large combinations and permutations.  If you've ever wondered about the millionth (or billionth,  or trillionth) permutation of the letters of the alphabet, this program is just for you.  If you find a good application for this information,  let me know.

January 12, 2003:  Here is a marble game I ran across in one of those Christmas gift puzzle books, "1000 Playthinks",  Ivan Moscovich, Workman Publishing.   The objective of Rally  is to put the blue marbles where in red marbles are now by rotating marbles in their horizontal and/or  vertical tracks..   Might provide a few minutes entertainment solving it, maybe more if you want to find the minimal 3 move solution.  And even more if you want to write the code to dynamically generate that track and animate the marbles!

January 10, 2003:  I ran across an interesting site this week at  mathschallenge.net.   I'm not sure who sponsors it, but it seems to be a educational site with lots of math and programming problems.   (Probably British since "math" comes out "maths".)    I enrolled in  their "Project Euler";  a set of graded programming projects, at least 8 levels with 3 problems per level.  You must enter the correct numeric answer for  two of the three problems in a level to gain access to the next level.   I've completed the first 17 so far and the highest score is 21, so old "delphiforfun"  may be at the top of the list in another week.   Today it took about 6 hours to solve #17: "How many letters are in the written words for the numbers 1 to 1000?"   That time  includes about 4 hours of debugging to discover that I didn't know how to spell the word for 18.   How many "t"s do you think it has?

I'm posting this in case there are Delphi programmers out there who may want to take on the  challenge.  I plan to publish some of my solutions here (maybe odd or even numbered programs) and will certainly entertain feedback questions about those that I have completed.   If you do sign up, consider making "delphi" part of your handle  - maybe we can help subtly spread the word about what a great language it is!

January 5, 2003:    Happy new year!

I hope Santa was as good to everyone as he was to me.  A new Case Folding Hunter (hunting knife),  a binary clock,  a box of dark chocolate covered cherries, and several new puzzle and recreational math books.  Who could ask for anything more?

Here's is the first program on DFF not written by me.  Molecules is program which simulates molecular motion in several interesting ways.  Retired Science teacher Arne is a talented amateur Delphi programmer and correctly guessed that this program would appeal to me.  I  made a few minor changes but the majority of the code is as he wrote it.   I enjoyed it, hope you will too.

(Let me add that this is not an invitation to submit your favorite code.    Publishing other's code is not the most fun part of this job - but in this case I found the project interesting,  the code was written in my style, and Arne offered to buy me a beer if I ever come to visit his hometown.   One such offer every couple of years may be the limit.)