From mboxrd@z Thu Jan  1 00:00:00 1970
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Date: Fri, 18 Apr 2014 20:52:22 +0100
Message-ID: <CAGMcHPqONnwf6gB2ajEGseA2FE6fxjvJ4V6+zr2pr7kQUP3NYg@mail.gmail.com>
From: Riddler <riddler876@gmail.com>
To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net>
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Subject: [9fans] Floating point and dividing by 0
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Hello again,

Continuing on with my floating point adventures, I have a question that I
hope someone can provide some input on.

I'm general idea of what I'm doing the following:
    double zero = 0.0;
    notify(fpnotecatch); //Ignore divide by zero note for a moment
    double pInf = 1.0/zero;
    notify(0); //Back to default note handler

    if(isInf(pInf, 1) <= 0 && isInf(pInf, 0) <= 0) exits("Divide by zero
did not result in infinity");

The error "did not result in infinity" is always tripped. My understanding
is that according to the spec it should have resulted in either + or -
infinity.

I suspect it's not required as there was a note thrown instead, and I can't
think of any reason why you would deliberately ignore the note like I do of
the top of my head. Thought I would mention it anyway see what input you
guys had.

Regards,
Rid.

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<div dir=3D"ltr"><div><div><div>Hello again,<br><br></div>Continuing on wit=
h my floating point adventures, I have a question that I hope someone can p=
rovide some input on.<br><br></div>I&#39;m general idea of what I&#39;m doi=
ng the following:<br>
</div><div>=C2=A0=C2=A0=C2=A0 double zero =3D 0.0;<br></div><div>=C2=A0=C2=
=A0=C2=A0 notify(fpnotecatch); //Ignore divide by zero note for a moment<br=
></div><div>=C2=A0=C2=A0=C2=A0 double pInf =3D 1.0/zero;</div><div>=C2=A0=
=C2=A0=C2=A0 notify(0); //Back to default note handler<br><br></div>
<div>=C2=A0=C2=A0=C2=A0 if(isInf(pInf, 1) &lt;=3D 0 &amp;&amp; isInf(pInf, =
0) &lt;=3D 0) exits(&quot;Divide by zero did not result in infinity&quot;);=
<br></div><div><br></div><div>The error &quot;did not result in infinity&qu=
ot; is always tripped. My understanding is that according to the spec it sh=
ould have resulted in either + or - infinity.<br>
</div><div><br>I suspect it&#39;s not required as there was a note thrown i=
nstead, and I can&#39;t think of any reason why you would deliberately igno=
re the note like I do of the top of my head. Thought I would mention it any=
way see what input you guys had.<br>
<br>Regards,<br>Rid.<br></div></div>

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