IsItPrime Files

IsItPrime v1.6.0
26 August 2012
by NullCoding (Jaska)

http://ncprime.blogspot.com
http://sourceforge.net/projects/isitprime

///////////////////////////
About:

This is a small and basic, yet powerful and highly configurable prime-number tester.

Unlike other NCPrime applications, IsItPrime does not calculate a specific type of number. It tests whatever number you tell it to test.

Version 1.6.0 is a testing beta. It is considered stable enough to run on most modern Windows systems.

///////////////////////////
How to use:

1. Input a number in the box. 
2. Select a testing method using the radio buttons.
3. (Optional) check the box for displaying all factors and/or to play sound when a factor is found.
4. Press TEST!
5. Save your results if you wish. You can even Tweet them. 

///////////////////////////
Known issues:

One or both threads will sometimes (meaning rarely) fail to exit properly. This seems to happen randomly, although there is likely a reason. You can kill the IsItPrime*32 process through Task Manager if this happens. 

Hitting the PANIC button usually kills all three threads, but for some reason, not always.

There is a built-in check to see if the number is even, but it doesn't work yet. 

The STOP button does nothing. It might in the future.

///////////////////////////
Notes:

IsItPrime is multi-threaded. This does not mean it runs in separate processes, merely separate threads. These threads are independant, meaning they do not communicate (non-mutex) and therefore must each perform their own primality test.

This means that they both test different trial division numbers, starting at 2 and 3 respectively and increasing by 3 each time. Yes, this does mean it skips the number 4. This doesn't matter, since all numbers divisible by 4 are also divisible by 2. 

Sometimes, one thread will find several factors but the other finds none. They are "smart threads," so they check out each others' results immidiately before exiting to determine their exit behavior. If each finds out that the other found no factors, the number is said to be prime, whereas if one finds factors and the other does not, they point you to the other thread's results. 

Results files, when saved, will show all the factors regardless of which thread found them.

Additionally, tweets will not show results, merely the test number (and only if it's not too long!)

///////////////////////////
Brute-Force

Only brute-force trial division currently has the option to show every factor. This is entirely optional, but useful if your primary goal is to factor a number. 

It will warn you about length and computation time regardless of how big the candidate number actually is. However, it's got a point - large numbers can take several minutes to several hours or longer to test! Since there is essentially no limit to the length of the number you can input, be careful. The application is stable, but CPU-intensive. Memory usage is dealt with well enough and should NOT be a problem.