Thomas Koenig <tkoenig@netcologne.de> writes:Keith Thompson <Keith.S.Thompson+u@gmail.com> schrieb:>Chris Ahlstrom <OFeem1987@teleworm.us> writes:>Lynn McGuire wrote this screed in ALL-CAPS:>xkcd: Day Counter>
https://xkcd.com/3228/
>
Yes, floating point errors are the bane of my life ! Not so much now
with double precision but the single precision days were nightmares.
Well these days we have long double.
C has had long double as a standard type since the original 1989
ANSI C standard. (K&R1, 1978, didn't have long double.)
>
But wider floating-point types don't eliminate rounding errors.
Nor does "long double" have to be any more accurate thean
"double". C's type system leaves something to be desired
in that respect.
>
Fortran showed how it's done with its kind numbers and
SELECTED_REAL_KIND function - you ask for a certain minimum
precision, and the compiler either gives it to you, or your program
fails at compile time.
You can do the same thing in C or C++ with a compile-time test.
>
#include <float.h>
>
#if LDBL_DIG < 18
#error "long double doesn't have enough precision"
#endif
Not quite the same. SELECTED_REAL_KIND gives you the
_minimum_ real type for your requirements.
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| Date | Sujet | # | Auteur | |
| 4 Apr 26 |  xkcd: Day Counter | 26 | Lynn McGuire | |
| 4 Apr 26 |  Re: xkcd: Day Counter | 12 | Your Name | |
| 4 Apr 26 |  Re: xkcd: Day Counter | 8 | Lawrence D’Oliveiro | |
| 4 Apr 26 |  Re: xkcd: Day Counter | 7 | Nioclás Pól Caileán de Ghloucester | |
| 4 Apr 26 |  Re: xkcd: Day Counter | 6 | Lawrence D’Oliveiro | |
| 5 Apr 26 | Re: xkcd: Day Counter | 4 | Nioclás Pól Caileán de Ghloucester | |
| 5 Apr 26 | Re: xkcd: Day Counter | 3 | Lawrence D’Oliveiro | |
| 6 Apr 26 | Re: xkcd: Day Counter | 2 | Nioclás Pól Caileán de Ghloucester | |
| 6 Apr 26 |  Re: xkcd: Day Counter | 1 | Lawrence D’Oliveiro | |
| 8 Apr 26 | Re: xkcd: Day Counter | 1 | Nioclás Pól Caileán de Ghloucester | |
| 4 Apr 26 | Re: xkcd: Day Counter | 1 | Paul S Person | |
| 6 Apr 26 | Re: xkcd: Day Counter | 2 | Stuart Redmann | |
| 6 Apr 26 | Re: xkcd: Day Counter | 1 | Paul S Person | |
| 4 Apr 26 | Re: xkcd: Day Counter | 2 | Tony Nance | |
| 4 Apr 26 | Re: xkcd: Day Counter | 1 | Mark Jackson | |
| 4 Apr 26 | Re: xkcd: Day Counter | 1 | Jay Morris | |
| 5 Apr 26 | Re: xkcd: Day Counter | 9 | Chris Ahlstrom | |
| 5 Apr 26 | Re: xkcd: Day Counter | 8 | Keith Thompson | |
| 6 Apr 26 | Re: xkcd: Day Counter | 7 | Thomas Koenig | |
| 6 Apr 26 | Re: xkcd: Day Counter | 3 | Keith Thompson | |
| 6 Apr 26 | Re: xkcd: Day Counter | 2 | Thomas Koenig | |
| 6 Apr 26 | Re: xkcd: Day Counter | 1 | Keith Thompson | |
| 6 Apr 26 | Re: xkcd: Day Counter | 3 | Nioclás Pól Caileán de Ghloucester | |
| 6 Apr 26 | Re: xkcd: Day Counter | 2 | Lawrence D’Oliveiro | |
| 7 Apr 26 | Re: xkcd: Day Counter | 1 | J-P. Rosen | |
| 6 Apr 26 | Re: xkcd: Day Counter | 1 | candycanearter07 |
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