From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.ciao.gmane.io!not-for-mail From: Mauro Aranda Newsgroups: gmane.emacs.bugs Subject: bug#41223: 28.0.50; Calc gives wrong determinant for some matrices with symbolic variables Date: Wed, 13 May 2020 19:15:48 -0300 Message-ID: References: Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="000000000000ef10a905a58eec31" Injection-Info: ciao.gmane.io; posting-host="ciao.gmane.io:159.69.161.202"; logging-data="84543"; mail-complaints-to="usenet@ciao.gmane.io" Cc: 41223@debbugs.gnu.org To: Mattias =?UTF-8?Q?Engdeg=C3=A5rd?= Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Thu May 14 00:17:11 2020 Return-path: Envelope-to: geb-bug-gnu-emacs@m.gmane-mx.org Original-Received: from lists.gnu.org ([209.51.188.17]) by ciao.gmane.io with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1jYzgd-000Lr4-1m for geb-bug-gnu-emacs@m.gmane-mx.org; Thu, 14 May 2020 00:17:11 +0200 Original-Received: from localhost ([::1]:45926 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jYzgb-00035M-Um for geb-bug-gnu-emacs@m.gmane-mx.org; 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charset="UTF-8" Content-Transfer-Encoding: quoted-printable Mattias Engdeg=C3=A5rd writes: Hello Mattias. > Thank you for reporting this. If Calc cannot compute something, at least it shouldn't lie. Agreed. And thank you for taking care of this so quickly. > In this case I'm tempted to apply the expedient below. Would that suffice for you? > > --- a/lisp/calc/calc-mtx.el > +++ b/lisp/calc/calc-mtx.el > @@ -275,7 +275,7 @@ math-do-matrix-lud > k (1+ k))) > (setcar (nthcdr j (nth i lu)) sum) > (let ((dum (math-lud-pivot-check sum))) > - (if (Math-lessp big dum) > + (if (or (math-zerop big) (Math-lessp big dum)) > (setq big dum > imax i))) > (setq i (1+ i))) It is good enough for me. Thanks. Best regards, Mauro. --000000000000ef10a905a58eec31 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Mattias Engdeg=C3=A5rd <mattiase@acm.org> writes:

Hello Mattias.

> Tha= nk you for reporting this. If Calc cannot compute something, at least it sh= ouldn't lie.

Agreed.=C2=A0 And thank you for taking care of this= so quickly.

> In this case I'm tempted to apply the expedien= t below. Would that suffice for you?
>
> --- a/lisp/calc/calc-m= tx.el
> +++ b/lisp/calc/calc-mtx.el
> @@ -275,7 +275,7 @@ math-= do-matrix-lud
> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2= =A0 k (1+ k)))
> =C2=A0 =C2=A0 =C2=A0 =C2=A0 (setcar (nthcdr j (nth i= lu)) sum)
> =C2=A0 =C2=A0 =C2=A0 =C2=A0 (let ((dum (math-lud-pivot-c= heck sum)))
> - =C2=A0 =C2=A0 =C2=A0 =C2=A0 (if (Math-lessp big dum)<= br>> + =C2=A0 =C2=A0 =C2=A0 =C2=A0 (if (or (math-zerop big) (Math-lessp = big dum))
> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 (setq bi= g dum
> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2= =A0 =C2=A0 imax i)))
> =C2=A0 =C2=A0 =C2=A0 =C2=A0 (setq i (1+ i)))
It is good enough for me.=C2=A0 Thanks.

Best regards,
Mauro= .
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