What's New - June, 2007
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June 29, 2007: Need more Graph Theory? A "minimal spanning tree" would be a good way to lay out a pipeline or cable service to a set of locations from a central site. It would not be a good route for a traveling salesman! A young Chinese student has an assignment to explain both Prim's and Kruskal's Algorithms for finding minimal spanning trees using code samples from any source. I had several emails from him asking for help waiting when I returned from vacation. Today I added a Prim's button to the the Minimal Spanning Tree Demo program which had already contained Kruskal's method. Prim's actually predates Kruskal's, is simpler, and slower.
June 28, 2007: Back from vacation. We had a great time. Kauai, the Garden Isle, was our favorite although everyone agrees that we need at least a week per island next time. We did all of the normal tourist stuff: swimming, snorkeling, helicopter rides, hiking, and, for the girls in the family, shopping of course! Only a half dozen or so emails requiring action so I'll be getting to those in the next few days.
June 14, 2007: We're off on vacation! Hawaii this year with all the kids, kids-in-law, and grandkids. We're doing the 7 day cruise ship tour that visits each of the 4 major islands for a day or two. This is our 2nd extended family vacation and I just hope this one is as successful as the last. The occasions when everyone can make it will be harder to arrange as the grandkids grow up (our oldest granddaughter starts college this fall). Dang, I don't feel that old!
I'll catch up on your feedback emails when we get back home.
In addition to checking and worrying about travel arrangements this week, I did find time to finish one more program; an electronic tuner called FFT_Tuner. The FFT stands for "Fast Fourier Transform", a "magic" technique which converts a set of numbers representing the amplitude of a signal over to time into a set of frequencies, amplitudes, and phases which if added back together would approximate the original input. This program simply displays the frequency with the largest amplitude, updated about once per second. You can read more about it and/or download the executable program and the source code at the above link.
June 10, 2007: Print Preview Demo Program V2.0:
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Version 2 of our Print Preview demo program was posted today in the Delphi Techniques section. The preview unit previews memo string data and string grids as they will appear when printed (and allows you to print them). The primary new feature is to automatically break a string grid when it crosses a page boundary and repeats the column header cells at the top of each continued page.
June 4, 2007: Here's one for the Delphi programmers out there. I recently investigated techniques for rearranging listbox items using drag/drop mouse movements (moving the mouse over an item to be moved and then holding left mouse button down while dragging it to a new location). ArrangeListBox describes and provides source code for three versions, from simplest (12 lines of user code) to one which has the features I wanted (visual indication of drop point and "auto-scroll" to drag across multiple pages; 150 lines of user code).