From: | Bruce Momjian <bruce(at)momjian(dot)us> |
---|---|
To: | Roman Kononov <kononov195-pgsql(at)yahoo(dot)com> |
Cc: | PostgreSQL-patches <pgsql-patches(at)postgresql(dot)org> |
Subject: | Re: [BUGS] BUG #2846: inconsistent and confusing handling of |
Date: | 2006-12-27 22:04:34 |
Message-ID: | 200612272204.kBRM4Yw13461@momjian.us |
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Lists: | pgsql-hackers pgsql-patches |
Roman Kononov wrote:
> On 12/27/2006 03:23 PM, Bruce Momjian wrote:
> > Are you sure? As I remember, computation automatically upgrades to
> > 'double'. See this program and output:
>
> This is platform- and compiler- dependent:
>
> ~>uname -a
> Linux rklinux 2.6.15-27-amd64-generic #1 SMP PREEMPT Fri Dec 8 17:50:54 UTC 2006 x86_64 GNU/Linux
> ~>gcc --version
> gcc (GCC) 4.3.0 20061213 (experimental)
> Copyright (C) 2006 Free Software Foundation, Inc.
> This is free software; see the source for copying conditions. There is NO
> warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
>
> ~>cat test.c
> #include <stdio.h>
> #include <stdlib.h>
>
> int
> main(int argc, char *argv[])
> {
> float a = 1e30, b = 1e30;
> double c;
>
> c = a * b;
>
> printf("%e\n", c);
> return 0;
> }
> ~>gcc test.c
> ~>./a.out
> inf
> ~>gcc -march=i386 -m32 test.c
> ~>./a.out
> 1.000000e+60
Interesting. I didn't know that, but in the float4pl() function,
because the overflow tests and result is float4, what value is there to
doing things as double --- as soon as the float4 maximum is exceeded, we
throw an error?
--
Bruce Momjian bruce(at)momjian(dot)us
EnterpriseDB http://www.enterprisedb.com
+ If your life is a hard drive, Christ can be your backup. +
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