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From: Maxim Cournoyer <maxim.cournoyer@gmail.com>
To: Diego Nicola Barbato <dnbarbato@posteo.de>
Cc: 40406-done@debbugs.gnu.org
Subject: bug#40406: python-matplotlib fails to build on i686-linux
Date: Sat, 14 Nov 2020 22:14:08 -0500	[thread overview]
Message-ID: <877dqnfh1b.fsf@gmail.com> (raw)
In-Reply-To: <87zh9d8wn7.fsf@GlaDOS.home> (Diego Nicola Barbato's message of "Mon, 08 Jun 2020 16:22:52 +0200")

Hello Diego,

Diego Nicola Barbato <dnbarbato@posteo.de> writes:

> Hey,
>
> Diego Nicola Barbato <dnbarbato@posteo.de> writes:
>
> [...]
>
>> Apparently there is nothing wrong with the slider.  Instead matrix
>> multiplication, which is used under the hood for transformations, seems
>> to sometimes produce incorrect results on i686-linux.  I have reported
>> this as a separate bug (https://debbugs.gnu.org/41665).
>
> I got this wrong: This issue isn't caused by the Numpy bug, since
> Matplotlib doesn't use Numpy for transformations.  Both bugs are caused
> by the excess precision of the x87 FPU's floating point registers.
>
> I've attached a patch which makes sure that the C and C++ extensions are
> compiled with -ffloat-store.  This doesn't get rid of all possible
> rounding errors but it's enough for the slider test to pass.

Thanks for the investigationd and workaround!  I've tested it and it
seems to work well.  I've pushed a slightly modified version to master
as commit 81643c4cf3e61f5a98b92a72a92c230f5e7ca905.

Thank you!

Closing.

Maxim




      reply	other threads:[~2020-11-15  3:15 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-03 15:20 bug#40406: python-matplotlib fails to build on i686-linux Diego Nicola Barbato
2020-04-03 16:18 ` Leo Famulari
2020-06-02 16:18   ` Diego Nicola Barbato
2020-06-02 17:39     ` Leo Famulari
2020-06-08 14:22     ` Diego Nicola Barbato
2020-11-15  3:14       ` Maxim Cournoyer [this message]

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