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Groups > comp.lang.java.programmer > #35770

Re: double == double

From Eric Sosman <esosman@comcast-dot-net.invalid>
Newsgroups comp.lang.java.programmer
Subject Re: double == double
Date 2016-10-15 14:15 -0400
Organization A noiseless patient Spider
Message-ID <nttroe$of4$1@dont-email.me> (permalink)
References (3 earlier) <87zim5es30.fsf@golem.phantasia.org> <ntta21$osp$1@dont-email.me> <nttemi$mt3$1@gioia.aioe.org> <nttfev$bgj$1@dont-email.me> <nttlum$u6r$2@dont-email.me>

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On 10/15/2016 12:36 PM, 4ndre4 wrote:
> [...] I was
> developing a 3D geometry library in C++ a while ago. The problem I had
> was testing the library. I had to test for equality with 0.0 when
> checking whether a point belonged to a plane or a rect was the result of
> the intersection between two planes. Determining the delta to use turned
> out to be extremely difficult, if not impossible. I ended up tranforming
> my classes into templates with a generic type for the coordinate, and
> write tests using integers instead of doubles. I'd be curious to know if
> there can be a better solution.

<topicality level="marginal">

     Although it covers only the two-dimensional case, this paper

http://www.cpsc.ucalgary.ca/~marina/papers/Segment_intersection.ps

describes some techniques you might find (or might have found) useful.
In particular, it offers a method of determining *exactly* whether a
sum of floating-point values would be negative, zero, or positive if
it were carried out in perfect precision.

</topicality>

-- 
esosman@comcast-dot-net.invalid
"Everybody must get stoned."  Looks like the Swedish Academy was.

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Thread

Re: double == double Eric Sosman <esosman@comcast-dot-net.invalid> - 2016-10-12 09:39 -0400
  Re: double == double Michael Jung <miju@golem.phantasia.org> - 2016-10-13 21:10 +0200
    Re: double == double Michael Jung <miju@golem.phantasia.org> - 2016-10-15 14:04 +0200
      Re: double == double Eric Sosman <esosman@comcast-dot-net.invalid> - 2016-10-15 09:13 -0400
        Re: double == double Arne Vajhøj <arne@vajhoej.dk> - 2016-10-15 10:32 -0400
          Re: double == double Eric Sosman <esosman@comcast-dot-net.invalid> - 2016-10-15 10:46 -0400
            Re: double == double Michael Jung <miju@golem.phantasia.org> - 2016-10-15 17:44 +0200
            Re: double == double 4ndre4 <626401fd-4bc7-4f8f-b641-563ae0f72920@626401fd-4bc7-4f8f-b641-563ae0f72920.invalid> - 2016-10-15 17:36 +0100
              Re: double == double Eric Sosman <esosman@comcast-dot-net.invalid> - 2016-10-15 14:15 -0400
                Re: double == double 4ndre4 <626401fd-4bc7-4f8f-b641-563ae0f72920@626401fd-4bc7-4f8f-b641-563ae0f72920.invalid> - 2016-10-15 19:41 +0100
            Re: double == double Arne Vajhøj <arne@vajhoej.dk> - 2016-10-15 20:39 -0400
      Re: double == double Arne Vajhøj <arne@vajhoej.dk> - 2016-10-15 10:41 -0400
        Re: double == double 4ndre4 <626401fd-4bc7-4f8f-b641-563ae0f72920@626401fd-4bc7-4f8f-b641-563ae0f72920.invalid> - 2016-10-15 23:09 +0100
          Re: double == double Eric Sosman <esosman@comcast-dot-net.invalid> - 2016-10-15 18:28 -0400
            Re: double == double 4ndre4 <626401fd-4bc7-4f8f-b641-563ae0f72920@626401fd-4bc7-4f8f-b641-563ae0f72920.invalid> - 2016-10-16 03:13 +0100
              Re: double == double Eric Sosman <esosman@comcast-dot-net.invalid> - 2016-10-16 08:37 -0400
                Re: double == double 4ndre4 <626401fd-4bc7-4f8f-b641-563ae0f72920@626401fd-4bc7-4f8f-b641-563ae0f72920.invalid> - 2016-10-16 14:06 +0100
          Re: double == double Arne Vajhøj <arne@vajhoej.dk> - 2016-10-15 20:30 -0400
            Re: double == double 4ndre4 <626401fd-4bc7-4f8f-b641-563ae0f72920@626401fd-4bc7-4f8f-b641-563ae0f72920.invalid> - 2016-10-16 03:16 +0100
              Re: double == double 4ndre4 <626401fd-4bc7-4f8f-b641-563ae0f72920@626401fd-4bc7-4f8f-b641-563ae0f72920.invalid> - 2016-10-16 03:18 +0100
              Re: double == double Arne Vajhøj <arne@vajhoej.dk> - 2016-10-16 09:45 -0400
                Re: double == double 4ndre4 <626401fd-4bc7-4f8f-b641-563ae0f72920@626401fd-4bc7-4f8f-b641-563ae0f72920.invalid> - 2016-10-16 14:51 +0100
                Re: double == double Arne Vajhøj <arne@vajhoej.dk> - 2016-10-16 11:24 -0400
                Re: double == double 4ndre4 <626401fd-4bc7-4f8f-b641-563ae0f72920@626401fd-4bc7-4f8f-b641-563ae0f72920.invalid> - 2016-10-16 16:43 +0100
                Re: double == double Arne Vajhøj <arne@vajhoej.dk> - 2016-10-16 12:54 -0400
                Re: double == double 4ndre4 <626401fd-4bc7-4f8f-b641-563ae0f72920@626401fd-4bc7-4f8f-b641-563ae0f72920.invalid> - 2016-10-16 18:37 +0100
                Re: double == double Arne Vajhøj <arne@vajhoej.dk> - 2016-10-16 14:14 -0400
                Re: double == double 4ndre4 <626401fd-4bc7-4f8f-b641-563ae0f72920@626401fd-4bc7-4f8f-b641-563ae0f72920.invalid> - 2016-10-16 22:19 +0100
                Re: double == double Arne Vajhøj <arne@vajhoej.dk> - 2016-10-16 22:49 -0400
                Re: double == double a.laforgia@gmail.com - 2016-10-17 01:53 -0700
                Re: double == double Patrick Roemer <sangamon@netcologne.de> - 2016-10-17 19:04 +0200
                Re: double == double 4ndre4 <626401fd-4bc7-4f8f-b641-563ae0f72920@626401fd-4bc7-4f8f-b641-563ae0f72920.invalid> - 2016-10-17 20:17 +0100
                Re: double == double Patrick Roemer <sangamon@netcologne.de> - 2016-10-17 23:11 +0200
                Re: double == double 4ndre4 <626401fd-4bc7-4f8f-b641-563ae0f72920@626401fd-4bc7-4f8f-b641-563ae0f72920.invalid> - 2016-10-17 22:46 +0100
                Re: double == double Patrick Roemer <sangamon@netcologne.de> - 2016-10-18 18:55 +0200
                Re: double == double 4ndre4 <626401fd-4bc7-4f8f-b641-563ae0f72920@626401fd-4bc7-4f8f-b641-563ae0f72920.invalid> - 2016-10-18 18:52 +0100
                Re: double == double Patrick Roemer <sangamon@netcologne.de> - 2016-10-20 15:03 +0200
                True O-O [Was: double == double] Eric Sosman <esosman@comcast-dot-net.invalid> - 2016-10-17 18:06 -0400
                Re: True O-O Patrick Roemer <sangamon@netcologne.de> - 2016-10-18 18:32 +0200
                Re: True O-O [Was: double == double] Arne Vajhøj <arne@vajhoej.dk> - 2016-10-19 22:09 -0400
                Re: double == double Arne Vajhøj <arne@vajhoej.dk> - 2016-10-19 21:58 -0400
                Re: double == double Patrick Roemer <sangamon@netcologne.de> - 2016-10-17 18:58 +0200
                Re: double == double 4ndre4 <626401fd-4bc7-4f8f-b641-563ae0f72920@626401fd-4bc7-4f8f-b641-563ae0f72920.invalid> - 2016-10-17 20:32 +0100
                Re: double == double Patrick Roemer <sangamon@netcologne.de> - 2016-10-17 23:21 +0200
                Re: double == double Arne Vajhøj <arne@vajhoej.dk> - 2016-10-19 21:38 -0400
                Re: double == double Arne Vajhøj <arne@vajhoej.dk> - 2016-10-19 21:47 -0400
                Re: double == double Patrick Roemer <sangamon@netcologne.de> - 2016-10-20 15:01 +0200

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