What's New -  February, 2015

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February 2, 2015:  Two small updates this week.  If you already have these programs but haven't seen the problems fixed, it's probably not worth the time to download. 

Logic Problem Solver  V5.5 fixes a problem a user was having saving a new logic case.  Making the automatic backup copy of the existing file with that name failed under some conditions.           

The Unscramble V2.2, program, part of our Wordstuff collection, corrects range of maximum and minimum word lengths to find.  It now keeps them within the valid range based on the length of the current scrambled word. 

 February 10:  The RSA Key algorithm is well known to those involved with securely exchanging data electronically.  I implemented my demo version because I wanted to see how it worked and "just for fun".  RSA  Public Key Demo V2.1 was posted today fixing a subtle bug which occasionally generated RSA keys so secure that the encrypted data could never be decrypted!   I had never encountered the error myself, but a sharp user did and even provided a program to replicate the error. 

February 15, 2015:  Having survived Friday the 13th, I resurrected this Friday the 13th program  to check for other occurrences this year and discovered that we have two more (in March and November).  That's the maximum that can occur in a year and we won't see three in a year again until 2026, then 2037.   It's an interesting mental exercise to understand why there are 11 year gaps going forward but only 6 years since the last occurrence when I first posted this program in in 2009.  The program is also useful for finding  occurrences of specific days and dates, e.g. when is the next time your birthday falls on your birth day?  

 February 18, 2015:  Several years ago I was attracted to the problem of locating objects from sensors which could measure distance to a target but had no idea about its direction.   Your GPS is an example of such a target which does the calculation by reading satellite signals containing timestamps allowing the device to calculate how far it is from each satellite.  It takes 4 such satellite signals to determine a location using mathematics similar to those contained in my program, Point from 4 Sensors.   A viewer recently reported an error in a sample sensor equation in the web page description, although the implementation in the program was correct.  In the process of verifying (and correcting) the web page error, I cleaned up a couple problems with  program displays caused by my use of text scaling on my monitor. Since I had the program open anyway, I fixed those and posted the update today as Version 5.1.