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WHAT'S NEW
January 27, 2012: Here are a couple of interesting
probability problems solved analytically (describing the logic leading to the
solution) and experimentally (running a million trials of a simulation model),
Fifty Probability
Problems presents two problems about ladder tournaments.
Plans are to add more of the 50 in the future. January 18, 2012:
A Delphi programmer recently requested information about
determining the slope of the regression line through a set of (X, Y) data
points. It seemed like something I must have written and posted in the 11
years the site has been around but that doesn't seem to be the case. So
here is LinearLeastSquares
which takes a set of points, plots them and draws the "best fit" regression
line. It also displays the equation of the line and Correlation
Coefficient, R (actually R2, called the Coefficient of
Determination) indicating how well the data are linearly related.
January 12, 2012: Logic Solver a program that can help solve many logic problems commonly found in puzzle magazines and books. Here is a simple example: Mary, John and Pete have red, brown, and blonde hair,
and are 13, 14, and 15 years old . Using the following clues
determine the hair color, and age of each child. From these facts the program can apply rules of logic to match the children up with their ages and hair color. Previous versions would handle up to 100 facts; Logic Solver Version 3.3 posted the other day solves problems at least twice as large as the previous version. Click the link to see the rest of the story.
January 11, 2012:
Robot Rooms implements
an algorithm for exactly covering a rectangular area with random rectangles
meeting certain size and shape constraints. Earlier exact covering
algorithms tended to generate many long and skinny rectangles or with a large
range of sizes. Neither of those properties are desired if we want to design dungeons or
rooms for robots to explore!.
December 18, 2011: Whew! It has been a busy month between deer hunting, Christmas preparations, and educating myself about how satellites manage to orbit the earth. A decent little 4 point buck is in the freezer, the Mission style bookcase for the wife's scrapbooks finished, and Earth-Sat Satellite Simulator Version 1 was posted today. Of the three activities, the
simulator took the most time by far, but I now have a pretty good handle on how
and why satellites manage to stay in the sky. I'll be checking and
cleaning up the documentation in the next day or two, but I believe the
program is in pretty good shape.
December 4, 2011: The original Drag Strip
"Christmas Tree" program simulates the sequenced lights used to control drag
race starts. I recently enhanced the program to drive real lights on a
real model tree using a USB relay board for a drag car owner and
enthusiast. . See
Dragster Tree Relay
Version 2 for more details November 30, 2011: The Four Fours problem
requires that digits 4444 be combined with mathematical operations to form
expressions which evaluate to all values from 0 to 100. I couldn't do it
using +,-,*,/,^ operations (other "cheats" are required). I did generalize
the problem so that my Four
Fours version does find 4 digit solutions for smaller target ranges or 5
digit solutions for all 101 targets..
November 13, 2011: Another small feature
upgrade for our Brute Force Solver program today. In
Brute Force Version 2.6, you can specify
the allowed solution integers as a range ( for example. 1-5 instead of
1,2,3,4,5. Today's Mensa Calendar Puzzle "Alphametics"
problem is also
included in the sample problem download files as a test case.. Just enter
NOW+NOW+NO=CHOW into the program to find the answer. November 10, 2011: If you are into search
algorithms, here's one,
Branch and Bound, which demonstrates "Exhaustive" and "Branch and Bound"
search methods for finding the
best solution for "Knapsack" problems. It was adapted with the author's kind
permission from the book "Ready-to-Run Delphi 3.0 Algorithms", Rod Stephens,
Wiley Computer Publishing. The Knapsack Problem requires that we figuratively fill a knapsack by
selecting from a set of items whose
weight (or other "cost" measurement) and value (or "profit") are known.
The objective is to maximize the value (profit) of the items in the sack without
exceeding a predefined weight (cost) limit. The "Branch and Bound" method
is orders of magnitude faster than Exhaustive search for large cases. October 30, 2011: A batch (command line) version of our Clear Blank Lines utility program was posted today to help a user who needs to run the program repetitively. The program removes lines from user selected text files which are entirely blank. Batch files can be a pain in the "you-know-what" to set up but are an convenient way to repetitively run a program without user interaction. Parameters in this version allow masked searches for files to be processed including ability to search subdirectories, and to make backups of files which are changed. The download includes sample test files and a batch file to process them. October 21, 2011: Scrambled Letter Blocks was posted today in our Delphi Techniques section. The puzzle is from the October 17 page of my 2011 Mensa 365 Brain Puzzlers Calendar
"Form six 9-letter words by combining two 3-letter blocks below with each ending already placed in the grid. All blocks will be used. If you do it correctly, one of the vertical columns will spell a bonus word. Use these groups to complete the words in the grid: AFT, ARC, BET, DEM, ERG, HEN, KEB, ROT, SCO, SNA, UND, YST" | |||||||||
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I
posted another update today to a program included in our