View Single Post
Old 2006-05-28, 11:16   #3
K Ramsey
May 2006

716 Posts

Originally Posted by Uncwilly
I fired up Dario's handy Java app. and feed it all odd exponent to 501 and it took it ~2 seconds to check all the numbers for primality.

That is 2^3-1, 2^5-1, 2^7-1,..... 2^499-1, 2^501-1

I could not find a L-L in BASIC, but, I suspect that it would kick some serious speed, FFT & DWT not included.
I fed this program 2^4423 -1 and it took only about 5 seconds to print out all 1602 digits and that the number is prime! Is this really a good base mark to judge my program on?
I did improve the speed of my program a bit. It went through primes from 409 through 929 in less than 6.5 hours. I was afraid that it would take much longer so I put the numbers 521 and 607 ahead of 409 on my excel spread sheet last night to see if I didn't mess things up. I for got to remove them further down in the list so the program did these primes twice. About turning the screen update off to speed the program up, this might not applied to Excel 2003 as it was writen for Excel 97. This morning when I turned on my monitor nothing was showing beside 521 or 607 until I hit the escape button to exit the program. I was afraid at first that I screwed up and the program failed until the 1's showed up on the screen after I exited my program. I still have some improvements to make then I will trim down my program and export the module, delete it, and import it back into my workbook to see if that increases my speed. Of course all you experts out there may find this quite amusing. Are there really programs out there that can give the primeness of 2^4423 -1 on my Windows XP in less than 7 seconds without being based upon the predetermined fact of it?

Last fiddled with by K Ramsey on 2006-05-28 at 11:20
K Ramsey is offline   Reply With Quote