[GAP Forum] bug in LLLReducedGramMat? II

[Benjamin Sambale]

Yes, that is basically what I mean. Usually, I'm not interested in basis 
vectors of lattices. I just want to transform a symmetric matrix M via 
SMS^t so that the resulting matrix has "nicer" shape. In this sense the 
following non-semidefinite matrix "works" perfectly:

LLLReducedGramMat([[1,2],[2,1]]);
rec( B := [ -3, 1 ], mue := [ [  ], [ 0 ] ], relations := [  ], 
remainder := [ [ -3, 0 ], [ 0, 1 ] ], transformation := [ [ -2, 1 ], [ 
1, 0 ] ] )

Best,
Benjamin

Am 31.10.2015 um 00:33 schrieb Dima Pasechnik:
> On Fri, Oct 30, 2015 at 11:23:40PM +0100, Bill Allombert wrote:
>> On Fri, Oct 30, 2015 at 09:11:15PM +0100, Benjamin Sambale wrote:
>>> Meanwhile, I figured that M in my last email is not positive
>>> semidefinite, and so it is not a Gram matrix as required in the
>>> manual. But since many other non-semidefinite matrices do work, one
>>> should at least change the error message.
>> I am curious, how do you define 'work' ?
> check this out:
>
> gap> M:=[[0,1],[1,0]];
> [ [ 0, 1 ], [ 1, 0 ] ]
> gap> LLLReducedGramMat(M);
> rec( B := [  ], mue := [  ], relations := [ [ 1, 0 ], [ 0, 1 ] ], remainder := [  ], transformation := [  ] )
> gap>
>
> I suppose "works" means "returns stuff", or "gives up silently"
> rather than "throws an error"
>
> Dima
>
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