Re: [sage-devel] Strange performance (bug?) computing a specific determinant | D. S. McNeil | 9/6/12 8:03 AM | > That said, I am wondering if this is perhaps a bug in the default implementation of determinant()?
> It seems strange to me that it takes 8 minutes to compute a determinant of a 34x34 matrix while other algorithms do it within a second. Yeah, it looks like pari's Gauss-Bareiss takes forever on this matrix, even though its classical Gaussian is quick: sage: time m2._det_pari(1) 336140000000000000 Time: CPU 0.00 s, Wall: 0.00 s sage: time m2._det_pari(0) 336140000000000000 Time: CPU 597.13 s, Wall: 597.10 s Kind of funny: _det_pari(0) is so slow on this particular matrix that it's five orders of magnitude faster to square m2 and take the root of the determinant! sage: %timeit (m2)._det_pari(1) 125 loops, best of 3: 3.39 ms per loop sage: %timeit (m2*m2)._det_pari(0)^(1/2) 125 loops, best of 3: 5.92 ms per loop Doug |

Re: [sage-devel] Strange performance (bug?) computing a specific determinant | Jernej Azarija | 9/6/12 2:03 PM | Interesting! I have also noticed that if I just slightly modify the matrix m2, it again works efficiently. Will someone direct the pariGP guys to this issue? |

Re: Strange performance (bug?) computing a specific determinant | Jernej Azarija | 1/2/13 9:11 AM | Hello! Has anyone already looked into this thing? The bug appears to slow down all matrix computations related to pariGP. For example it gets stuck computing the eigenvalues of a matrix as well. It's quite annoying. The pariGP guys confirmed it's a bug in pari so we should update the pari package that sage ships! Best, Jernej On Thursday, 6 September 2012 14:12:07 UTC+2, Jernej Azarija wrote: Consider the following program |

Re: [sage-devel] Re: Strange performance (bug?) computing a specific determinant | Jeroen Demeyer | 1/3/13 3:23 AM | On 2013-01-02 18:11, Jernej Azarija wrote:If you create a Sage ticket for this issue, pointing to the PARI/GP bug report and cc: me, I'll happily apply the fix. |

Re: [sage-devel] Re: Strange performance (bug?) computing a specific determinant | Jeroen Demeyer | 1/3/13 5:38 AM | I backported an upstream patch for this and made a new PARI spkg, needs
review at http://trac.sagemath.org/sage_trac/ticket/13902 |