Subject: Sums of digits and other tricks and factor()
From: Richard Hennessy
Date: Thu, 10 Dec 2009 19:05:27 -0500
My mistake. I don't know very much about how factor works.
Rich
From: Stavros Macrakis
Sent: Thursday, December 10, 2009 5:35 PM
To: Richard Hennessy
Cc: Maxima List
Subject: Re: [Maxima] Sums of digits and other tricks and factor()
The slow part of factoring 8788797887776565343256785434546789796543568097876592 into its prime factors is not in
finding the small factors 2^4*3*799760501, but the big ones 268141679222792839781*853815361070739347909. See
http://en.wikipedia.org/wiki/Integer_factorization for more background.
-s
On Thu, Dec 10, 2009 at 5:29 PM, Richard Hennessy <rich.hennessy at verizon.net> wrote:
I have been wondering why factor() is slow on factoring big exact numbers that are in the form y/x where x is a big
even integer and y is an integer. It is easy to tell that factor 8788797887776565343256785434546789796543568097876592
is factorable by 2 just by looking at the last digit.
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