20070406, 19:16  #1 
Apr 2007
4_{16} Posts 
Prime check need
Is there any site or program i can test if one array is prime number?You have to know that the array is very long number and the algoithm should be fast...Thank you in advance

20070406, 19:21  #2 
"Nancy"
Aug 2002
Alexandria
2,467 Posts 
What do you mean by "array?" Do you have an array of many large numbers to test, or maybe an array of "unsigned int" that form one large number? How large exactly is the number? Do you want a test that tells primality with extremely low, but nonzero probability of error, or does it have to be a mathematical proof?
Alex 
20070406, 20:32  #3 
Apr 2007
2^{2} Posts 
I mean string and "char" type.The lenght of the string is about 10 miliion symbols.Is there any software,code or algorithm to check if it is prime?

20070406, 21:25  #4 
Account Deleted
"Tim Sorbera"
Aug 2006
San Antonio, TX USA
4267_{10} Posts 
10 million symbols that are how many different things per symbol? This makes a huge difference. There could be two things per symbol, in which case your number is 2^10000000, or, for all we know, it could be 10 million different per symbol, making it 10000000^10000000. Please clarify by saying how many digits it is and what form of number it is (or the number itself if you don't mind saying it), so we can figure out what factoring/primality test would be the most efficient.

20070406, 23:32  #5 
∂^{2}ω=0
Sep 2002
República de California
2D60_{16} Posts 
If by "symbol" he means anything encoding a single bit or more, no, there is no known algorithm to test 10Msymbol numbers not having any special algebraic form for rigorous primality.
A probablyprime test might be within reach, if the symbols are decimal digits or smaller. 
20070407, 02:16  #6  
Jun 2005
USA, IL
193 Posts 
Quote:


20070407, 07:37  #7 
Apr 2007
2^{2} Posts 
The string contains about 10 million digits.I thought it isn't so difficult to understand.I read in this forum that i can test if the number is prime with prime95 program but first i should register myself in GIMPS project.Is it right?:surprised

20070407, 07:46  #8  
Apr 2007
2^{2} Posts 
Quote:


20070407, 10:37  #9  
Banned
"Luigi"
Aug 2002
Team Italia
11303_{8} Posts 
Quote:
If your number is not built on this form, you have no chance to test it. Also please note that if you use GIMPS to test your number, and the number is prime, you must share the EFF prize as explained here. Luigi Last fiddled with by ET_ on 20070407 at 10:38 

20070407, 11:06  #10  
Sep 2002
Database er0rr
2×7×257 Posts 
Quote:
Last fiddled with by paulunderwood on 20070407 at 11:06 

20070407, 15:26  #11 
"Nancy"
Aug 2002
Alexandria
2,467 Posts 
The question of whether you need a *proof* of primality, or merely a primality test with very small chance of error, is unanswered.
If you need the former, getting a positive result is out of the question, unless your number is of a very specific form. If the latter will do, PFGW sounds like a good way to go. Alex 
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