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Subject: |
flmax and flmin do not handle +nan.0 correctly |
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Date: |
Mon, 15 Jul 2013 13:11:47 +0200 |
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User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/23.4 (gnu/linux) |
Hello schemers,
the flmax and flmin procedures from (rnrs) do not handle +nan.0
correctly:
scheme@(guile-user)> (import (rnrs))
scheme@(guile-user)> (flmax +inf.0 +nan.0)
$1 = +inf.0
scheme@(guile-user)> (flmin -inf.0 +nan.0)
$2 = -inf.0
The result should be +nan.0. From r6rs-lib: "They always return a NaN
when one or more of the arguments is a NaN." Tested with
2.0.9.22-7e816-dirty.
Regards,
--
Göran Weinholt <address@hidden>
It's a beautiful day.
Don't let it get away.
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--- Begin Message ---
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Subject: |
Re: bug#14865: flmax and flmin do not handle +nan.0 correctly |
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Date: |
Tue, 16 Jul 2013 05:27:30 -0400 |
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User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) |
Göran Weinholt <address@hidden> writes:
> the flmax and flmin procedures from (rnrs) do not handle +nan.0
> correctly:
>
> scheme@(guile-user)> (import (rnrs))
> scheme@(guile-user)> (flmax +inf.0 +nan.0)
> $1 = +inf.0
> scheme@(guile-user)> (flmin -inf.0 +nan.0)
> $2 = -inf.0
>
> The result should be +nan.0. From r6rs-lib: "They always return a NaN
> when one or more of the arguments is a NaN."
Indeed. I had actually carefully implemented 'min' and 'max' according
to R6RS section 11.7.4 (Numerical operations), which states:
For any real number object x:
(max +inf.0 x) => +inf.0
(min -inf.0 x) => -inf.0
and section 3.5 states that NaNs are real number objects.
At first I was baffled by the inconsistency between min/max and
flmin/flmax, but now I see that the R6RS errata corrected this:
The examples for min and max involving infinities should be prefixed by:
"For any real number object x /that is not a NaN/:"
Fixed in b4c55c9ccedd47c16007b590f064ef3bd67565aa.
Thanks!
Mark
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