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Re: isnanl, printf, and non-IEEE values
From: |
Rich Felker |
Subject: |
Re: isnanl, printf, and non-IEEE values |
Date: |
Mon, 18 Jun 2012 13:50:51 -0400 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Mon, Jun 18, 2012 at 10:21:34AM -0700, Ben Pfaff wrote:
> Bruno Haible <address@hidden> writes:
>
> > In theory you would be right that data should be validated at the boundaries
> > of the program, that is, when they are read from outside sources. But no
> > program I know of does this for unconstrained floating-point numbers.
>
> That's an interesting point. GNU PSPP reads unconstrained
> "double"s from SPSS data files without validating them[*], since
This is not a problem. As long as you're assuming IEEE, all 64-bit
patterns are valid long double values. The issue only occurs for long
double, a type that's very different in both arithmetic properties and
representation between systems. On typical systems, it has padding
bits (which might or might not be required to be all-zero) as well as
bit combinations that are completely invalid.
> it never occurred to me that this was a bad idea. A function to
> validate a floating-point number would therefore be useful in
> PSPP.
It's only as useful as long doubles, which is, well, not very useful
to most people.
Rich
- Re: isnanl, printf, and non-IEEE values, (continued)
- Re: isnanl, printf, and non-IEEE values, John Spencer, 2012/06/18
- Re: isnanl, printf, and non-IEEE values, Eric Blake, 2012/06/18
- Re: isnanl, printf, and non-IEEE values, John Spencer, 2012/06/18
- Re: isnanl, printf, and non-IEEE values, Paul Eggert, 2012/06/18
- Re: isnanl, printf, and non-IEEE values, John Spencer, 2012/06/19
- Re: isnanl, printf, and non-IEEE values, Eric Blake, 2012/06/19
- Re: isnanl, printf, and non-IEEE values, Jim Meyering, 2012/06/19
- Re: isnanl, printf, and non-IEEE values, Paul Eggert, 2012/06/19
- Re: isnanl, printf, and non-IEEE values, Bruno Haible, 2012/06/17
- Re: isnanl, printf, and non-IEEE values, Ben Pfaff, 2012/06/18
- Re: isnanl, printf, and non-IEEE values,
Rich Felker <=
- Re: isnanl, printf, and non-IEEE values, Ben Pfaff, 2012/06/18
- Re: musl printf bugs, Bruno Haible, 2012/06/17
- Re: musl printf bugs, Rich Felker, 2012/06/17
- Re: musl printf bugs, Bruno Haible, 2012/06/17
- Re: getopt.m4 test, Bruno Haible, 2012/06/19
- Re: getopt.m4 test, Bruno Haible, 2012/06/23
- Re: getopt.m4 test, Paul Eggert, 2012/06/23
- Re: getopt.m4 test, Bruno Haible, 2012/06/26
Re: stdioext on musl, Bruno Haible, 2012/06/17