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 2015-11-17, 12:35 #1 paul0   Sep 2011 3916 Posts LLL in GP/Pari I'm trying the qflll function Pari for lattice reduction. However, I'm not getting correct answers. First, the wikipedia example: https://en.wikipedia.org/wiki/Lenstr...tion_algorithm Code: (20:32) gp > qflll([1,-1,3;1,0,5;1,2,6]) %50 = [-4 5 0] [-1 1 1] [ 1 -1 0] Second, the matlab example: http://www.mathworks.com/help/symboloddslotic/mupad_ref/lllint.html Code: (20:32) gp > qflll([1, 2, 3;4, 5, 6]) %51 = [-1 4] [ 1 -3] [ 0 0] As you can see, both results are incorrect. What am I doing wrong? Last fiddled with by paul0 on 2015-11-17 at 12:35
2015-11-17, 13:01   #2
WraithX

Mar 2006

11·43 Posts

Quote:
 Originally Posted by paul0 I'm trying the qflll function Pari for lattice reduction. However, I'm not getting correct answers. First, the wikipedia example: https://en.wikipedia.org/wiki/Lenstr...tion_algorithm Code: (20:32) gp > qflll([1,-1,3;1,0,5;1,2,6]) %50 = [-4 5 0] [-1 1 1] [ 1 -1 0] As you can see, both results are incorrect. What am I doing wrong?
Be sure to check the built-in documentation for what a function does, using either ?<func> or ??<func>:
Code:
?qflll
qflll(x,{flag=0}): LLL reduction of the vectors forming the matrix x (gives the
unimodular transformation matrix T such that x*T is LLL-reduced). flag is...
Doing the following works:
Code:
(06:54) gp > x=[1,-1,3;1,0,5;1,2,6]
%1 =
[1 -1 3]
[1  0 5]
[1  2 6]

(06:54) gp > qflll(x)
%2 =
[-4  5 0]
[-1  1 1]
[ 1 -1 0]

(06:54) gp > x*qflll(x)
%3 =
[0 1 -1]
[1 0  0]
[0 1  2]

2015-11-17, 13:04   #3
paul0

Sep 2011

5710 Posts

Quote:
 Originally Posted by WraithX Be sure to check the built-in documentation for what a function does, using either ? or ??: Code: ?qflll qflll(x,{flag=0}): LLL reduction of the vectors forming the matrix x (gives the unimodular transformation matrix T such that x*T is LLL-reduced). flag is...
Thank you :)

Last fiddled with by paul0 on 2015-11-17 at 13:04

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