Hi Simon, it seems to be a bug in Pari, the whole computation ends up calling
gflllgram(D._pari_(),1) which doesn't end. Constructing the same matrix directly in pari and calling the function there also doesn't end. I have tried changing the values for the flag and same behavior happens with flag values 0 (default), 1 (matrix of integers) and 4 (matrix of integers, give kernel and reduced image). However by setting the flag to 5 (matrix with polynomial entries) the computation is almost immediate: ? qflllgram(D,5) %4 = [[;], [15/4, 5/3, 1, 1, 1/2, 15; 3/2, 2/3, 1, 0, 1/2, 6; 3/4, 1/3, 0, 0, 1, 3; 5/4, 1, 0, 0, 0, 5; 1, 0, 0, 0, 0, 4; 0, 0, 0, 0, 0, 1]] We should probably report this bug upstream (unless is fixed on a more recent version of pari). Cheers, J On Monday, January 21, 2013 1:16:04 PM UTC, Simon King wrote: > > Hi Sage supporters, > > bump! > > Is there really no answer to Ian Hambleton's question that he asked a > month ago? > > Can it really be so difficult to do LLL_gram on a 6x6 integer matrix? > > Cheers, > Simon > > Am Donnerstag, 20. Dezember 2012 00:07:03 UTC+1 schrieb William: >> >> I'm forwarding this to sage-support... >> >> On Dec 19, 2012 8:52 AM, "Ian Hambleton" <hamb...@mcmaster.ca> wrote: >> > >> > Dear Professor Stein, >> > I am trying to use the Sage diagonalization routine found in: >> > >> > >> http://www.sagemath.org/doc/reference/sage/matrix/matrix_integer_dense.html >> > >> > The example given in the Sage documentation works fine, but the larger >> example below does not complete (hours later) on my machine, or in running >> Sage online through its webpage. >> > >> > Is this matrix too large, or have I made a mistake in the commands ? >> > >> > Any help you can provide would be most appreciated. >> > >> > best regards, >> > >> > Ian Hambleton >> > >> > PS: Is there a version which will accept matrices over finite fields or >> rings Z/n ? >> > >> > >> > sage: D=Matrix(IntegerModRing(), >> [[-1,1,0,1,1,0],[1,-3,1,0,0,0],[0,1,-2,0,0,0],[1,0,0,-3,0,0],[1,0,0,0,-4,1],[0,0,0,0,1,-5]]);D >> > [-1 1 0 1 1 0] >> > [ 1 -3 1 0 0 0] >> > [ 0 1 -2 0 0 0] >> > [ 1 0 0 -3 0 0] >> > [ 1 0 0 0 -4 1] >> > [ 0 0 0 0 1 -5] >> > sage: X = D.LLL_gram(); X >> > sage: X.transpose() * D * X >> > >> > >> > ----------------------------------------------------- >> > >> > Department of Mathematics & Statistics >> > >> > McMaster University >> > >> > 1280 Main St. West >> > >> > Hamilton, ON L8S 4K1, CANADA >> > >> > Phone: (905) 525-9140 x 27302 >> > >> > Fax: (905) 522-0935 >> > >> > Web: http://www.math.mcmaster.ca/ian/ian.html >> > >> > ----------------------------------------------------- >> > >> > >> > -- You received this message because you are subscribed to the Google Groups "sage-support" group. To post to this group, send email to sage-support@googlegroups.com. To unsubscribe from this group, send email to sage-support+unsubscr...@googlegroups.com. Visit this group at http://groups.google.com/group/sage-support?hl=en.
