Delphi For Fun Newsletter #3



Sunday Oct 8, 2000
How do you write the Australian pronunciation of "good day"?  The Olympics are over, but I've been communicating this week with a tutor who lives in New Zealand.   He writes like would speak with a similar accent.  He has provided some good feedback on first versions of the Scientific Grapher program.   I decided to go ahead and post the source code for this program, even though it won't compile on Delphi Standard.  It requires a version with the TChart charting component included in Delphi 5 Professional and Enterprise versions for sure, perhaps Delphi 4.  
The executable version if Sci-Grapher is available for download though.  It will run on any Win32 system (Win 95 and above).
Programs about two other topics were posted this week: Tetrahedrons and Permutations.
Tetrahedrons are triangular pyramids.  If you place three marbles on a flat surface all touching each other and place a 4th marble on top, you have made a tetrahedron.  The next larger size would have 6 marbles on the bottom, then 3 in a second layer and 1 on top for a total of 10.   If you continue building larger pyramids this way, there is only one other whose total number of marbles is the square of an integer.  We'll consider 1 to be the smallest with total of 1=1X1 marbles, the 4 marble pyramid is the second (4=2X2).   The program Triangular Pyramids finds the 3rd.  
The total number in these pyramids form a  sequence of tetrahedral numbers with many interesting properties (for example they always occur as 3 even numbers followed by an odd number).  The number of marbles in each layer form a sequence of triangular numbers, also very interesting.   There are only 5 numbers that are both tetrahedral and triangular. 
Three programs about permutations were posted.  Permutations are rearrangements of things.  The letters ABC can be rearranged in 6 ways - there are 6 permutations of 3 things.    Permutes1 introduces the topic and displays all permutations for a number that you enter.  (Well, within reason - there are over 3 1/2 million ways to arrange 10 things.  I don't think the program would print them all.)    Rotating Sums is a program that solves a particular problem for the digits 1-9 arranged in a 3X3 grid.  I'll let you go to the website for details.  Alphametics solves word arithmetic problems like ADAM+AND+EVE=MOVED where each letter stands for a different digit. 
That's it for this week.  We had our first snow flurries this morning, so I guess I had better go start getting up our winter's supply of wood.
700 viewers to date.
Gary Darby

If you find something you love doing as you're growing up, look hard to see if you can make a living at it instead of giving it up for something more sensible. -- Jennifer Lamb (stuntwoman)