bug#14865: flmax and flmin do not handle +nan.0 correctly

bug#14865: flmax and flmin do not handle +nan.0 correctly

[Göran Weinholt]

[-- Attachment #1: Type: text/plain, Size: 507 bytes --]

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 <goran@weinholt.se>
It's a beautiful day.
Don't let it get away.

[-- Attachment #2: Type: application/pgp-signature, Size: 835 bytes --]

bug#14865: flmax and flmin do not handle +nan.0 correctly

[Mark H Weaver]

Göran Weinholt <goran@weinholt.se> 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