Talk:Fermat's factorization method

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The 1st paragraph under sieve imrovements is very unclear. I assume some of these restrictions come about because of the value of N mod 20 etc? This should be explained. This paragraph needs to be expanded with a better step-by-step explanation. —Preceding unsigned comment added by 210.84.56.174 (talk) 02:52, 21 November 2007 (UTC)[reply]

The whole article is unclear... 10:55, 6 September 2008 (UTC)

Mod 16 optimization

Need to mention that the optimization section needs some remarks, there are more variants of a.
For each N mod 16, the a mod 16 must be as follows:

N mod 16	a mod 16
1 or D	1,7,9,F
3 or B	2,6,A,E
5 or 9	3,5,B,D
7 or F	0,4,8,C

-in order for a² - N to be square.
As you can notice, all even N are skipped - Fermat method does not test them.

Example in hexadecimal format:
Let N be 1751₁₆.
The right digit of N is 1, from table, right digit of a can only be 1,7,9 or F.
√1751₁₆ = 4E, so we test for a only 4F, 51, 57 and get result a² - N = 57₁₆² - 1751₁₆ as a perfect square.

Is this better than in the article? Got it clear now? Should this be in the article page?

--Neeme Vaino (talk) 20:20, 2 April 2010 (UTC)[reply]