From: "Mattias Engdegård" <mattiase@acm.org>
To: Mauro Aranda <maurooaranda@gmail.com>
Cc: 41223-done@debbugs.gnu.org
Subject: bug#41223: 28.0.50; Calc gives wrong determinant for some matrices with symbolic variables
Date: Thu, 14 May 2020 10:43:19 +0200 [thread overview]
Message-ID: <7A33094E-BD4C-45DE-A57D-F23D50CFC6B4@acm.org> (raw)
In-Reply-To: <CABczVwd2oGJJ+ph4FRMx+V4fcYG8T-dZVzUzpxAcnxA3+xdnJQ@mail.gmail.com>
14 maj 2020 kl. 00.15 skrev Mauro Aranda <maurooaranda@gmail.com>:
> It is good enough for me. Thanks.
The pleasure was all mine! It has now been pushed to master.
No doubt there are better ways of computing the determinant for non-numeric matrices. In particular, division shouldn't be necessary at all, and the current algorithm results in some untidy expressions. For example, the determinant of
[a 0 0 1]
[0 b 0 0]
[0 0 c 0]
[1 0 0 d]
is given as abc*(d-1/a), falsely giving the impression of being undefined for a=0, rather than bc(ad-1).
next prev parent reply other threads:[~2020-05-14 8:43 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-12 23:24 bug#41223: 28.0.50; Calc gives wrong determinant for some matrices with symbolic variables Mauro Aranda
2020-05-13 12:58 ` Mattias Engdegård
2020-05-13 22:15 ` Mauro Aranda
2020-05-14 8:43 ` Mattias Engdegård [this message]
2020-05-14 9:56 ` Mattias Engdegård
2020-05-14 11:49 ` Mauro Aranda
2020-05-14 11:41 ` Mauro Aranda
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