Re: [HACKERS] NAN code

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От jwieck@debis.com (Jan Wieck)
Тема Re: [HACKERS] NAN code
Дата
Msg-id m0zxF4G-000EBQC@orion.SAPserv.Hamburg.dsh.de
обсуждение исходный текст
Ответ на Re: [HACKERS] NAN code  ("Thomas G. Lockhart" <lockhart@alumni.caltech.edu>)
Список pgsql-hackers
>
> >     While  searching for the NAN definition I've noticed too that
> >     our float4/float8 datatypes can  output  'NaN',  but  do  not
> >     parse  them back.
>
> Yeah, I just noticed that a few minutes ago too.
>
> I've got some patches which fix this, at least for machines with NaN
> support (and for HUGE_VAL/Infinity too). We'll need some more code to
> handle non-IEEE machines...

    The  final  might  be  that  for  machines/compilers with NaN
    support, NAN is

        #define NAN (0.0/0.0)

    or whatever is the correct thing for it (best choice is still
    the definition from a system header like nan.h if available),
    while for those who cannot support it it'll be

        #define NAN unsupported_nan_request()

        double unsupported_nan_request(void)
        {
            elog(ERROR, "unsupported request for NaN as floating point value");
            return 0.0;
        }


Jan

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