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.
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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)
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