a program that writes the primes

hey, last night i made a program that will tell you whether or not a program is prime (with a lot of help from some other people, most notably RoD and Alpha) and i used it to create a basic program that lists out the amount of primes you specify, and, if its more that 300 (the amount of lines in the DOS window) it prints them to primes.txt. i was wondering how long it takes you guys for the program to print out a lot of them. for my 2.0 gig processer with i think 512 ram its instant up to about 10000 (ten thousand), and took close to 5 minutes for the first 200000(two hundred thousand). if you could download it and try it and give me some times, it would be appreciated. the program will tell you when the primes are written out.

Try posting source code...not many people (if any) will run executables.....i ran it, and 200,000 primes was a little under 3 minutes.....(phone rang, and when i came back, it was done, and it had hit the 3 minute mark)....XP 1700+ and 768 PC 2100

ok i will and thx for the input

I ran it on my PII 350 with 128 SD RAM with Windows 2000 pro, and it took close to 29 minutes to get to the 200,000 mark!! :(

Looks like it might be time to upgrade lol :rolleyes:

~ Paul

P3 1GHz, 512MB of RAM, 12min. I've put together a more efficient version, which only checks divisibility by prime numbers less than the square root, rather than all numbers less than the square root. On my PC, it spits out 200k primes in 19 seconds. I've attached the source if you wanna look at it.

mmm 12 seconds on XSquared's code :D

26 seconds with X squared's code on my "beast" (PII 350). :rolleyes:

I guess this is a really good way of testing how efficient your code is.

Edit: It would be fun to have a competition like this to see who could create the fastest/most efficient prime number generator, just everyones computer is different. Oh well.

~ Paul

Geo-Fry:

I didn't really look at your code, but I think it is writing the primes to disk as it computes them. If you want a real time for speed, you should only time the portion that computes the primes in memory, before taking disk writes into account. Also, I thought the program was going to do the timing for me, so I didn't time it accurately. It took approx. 3 minutes on my 1700+ XP athlon.

XSquared:

Those are definite improvements any prime-computing program should have. Your program took 13 seconds on my system.

jeeze, i guess xsquared is just too smart for me...
i looked at your code and i was like "WHOA! WTF IS THAT?" cause it was all wierd, so small and compact yet speedy and fast, your my hero