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Re: QuickFactorInteger

• To: mathgroup at smc.vnet.net
• Subject: [mg93842] Re: [mg93831] QuickFactorInteger
• From: Daniel Lichtblau <danl at wolfram.com>
• Date: Thu, 27 Nov 2008 05:28:06 -0500 (EST)
• References: <gfgqib$dm1$1@smc.vnet.net> <gfh3ca$g1d$1@smc.vnet.net> <200811140209.VAA16497@smc.vnet.net> <200811141136.GAA13071@smc.vnet.net> <200811261222.HAA22481@smc.vnet.net>

Artur wrote:
> Dear Mathematica Gurus,
> 
> Who know how construct procedure to obtained reasonable primes divisors 
> of big number in reasonable time. If number have two big primes divisors 
> range 40 decimal digits Mathematica function FactorInteger working hours 
> and do nothing. I want do time limit (e.g. 5 second) and received list 
> of factors which was obtained after these 5 seconds or do other  trick 
> to obtained partialy result of FactorInteger.
> 
> Best wishes
> Artur

Give a second argument of Automatic. This is similar to the 
pre-version-6 option FactorComplete->False.

Example:

In[10]:= p1 = NextPrime[10^40];

In[11]:= p2 = NextPrime[10^42];

In[12]:= p3 = Prime[2222];

In[13]:= p4 = Prime[5555555];

In[14]:= Timing[fax = FactorInteger[7*127*p1*p2*p3*p4, Automatic]]

Out[14]= {16.4915, {{7, 1}, {127, 1}, {19583, 1}, {96210113, 1}, 
{1000000000000000000000000000000000000012163000000000000000000000000000\
         0000000007623, 1}}}

Daniel Lichtblau
Wolfram Research

• Follow-Ups:
  • Re: Re: QuickFactorInteger
    • From: Andrzej Kozlowski <akoz@mimuw.edu.pl>

• References:
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    • From: Mayneord <xrayspectrum@googlemail.com>
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  • QuickFactorInteger
    • From: Artur <grafix@csl.pl>