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determinant() of integer matrices of size in [51,63] broken #14032

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jdemeyer opened this issue Jan 29, 2013 · 10 comments
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determinant() of integer matrices of size in [51,63] broken #14032

jdemeyer opened this issue Jan 29, 2013 · 10 comments
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@jasongrout @williamstein
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c: linear algebra p: critical / 2 t: bug
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sage-5.7

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@jdemeyer
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sage: random_matrix(ZZ,60).det()
[...]
RuntimeError: maximum recursion depth exceeded while calling a Python object

The problem was an infinite recursion where we compute a determinant over ZZ by working mod p and we compute a determinant over GF(p) by lifting to ZZ...

This recursion got broken because the bound to use LinBox for matrices mod p changed in #12883. This patch fixes this bound.

It also does various clean-up of doctests and removes _det_4x4_unsafe() which only added an extra level of indirection (determinant() -> _det_4x4_unsafe() -> four_dim_det())

Component: linear algebra

Author: Jeroen Demeyer

Reviewer: Volker Braun

Merged: sage-5.7.beta2

Issue created by migration from https://trac.sagemath.org/ticket/14032
@jdemeyer jdemeyer added this to the sage-5.7 milestone Jan 29, 2013
@vbraun
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vbraun commented Jan 29, 2013

comment:1

50 is the threshold for defaulting to algorithm='padic'. The following works fine: random_matrix(ZZ,60).determinant(algorithm='pari')

@jdemeyer
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comment:2

(never mind, forgot about caching)

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@jdemeyer jdemeyer changed the title determinant() of large integer matrices broken determinant() of integer matrices of size in [51,63] broken Jan 29, 2013
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comment:4

There is an infinite recursion going on where we compute a determinant over ZZ by working mod p and we compute a determinant over GF(p) by lifting to ZZ...

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@jdemeyer
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Author: Jeroen Demeyer

@jdemeyer
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comment:6

Attachment: 14032_multimodular_det.patch.gz

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vbraun commented Jan 30, 2013

comment:7

Looks great!

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vbraun commented Jan 30, 2013

Reviewer: Volker Braun

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Merged: sage-5.7.beta2

@jdemeyer jdemeyer mentioned this issue Feb 5, 2013
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