NetNews Offline 2/NetNews Offline Volume 2.iso/news/comp/std/c/59

Internet Message Format | 1996-08-06 | 1.6 KB

Path: lyra.csx.cam.ac.uk!nmm1
From: [e-mail] (Nick Maclaren)
Newsgroups: comp.std.c
Subject: Re: sizeof(1L) in preprocesor;How to tell sizeof(double)>sizeof(long) ?
Date: 9 Jan 1996 11:39:50 GMT
Organization: University of Cambridge, England
Message-ID: <4ctk66$[e-mail]>
References: <[e-mail]>  <[e-mail]>  <[e-mail]> <[e-mail]>
NNTP-Posting-Host: ursa.cus.cam.ac.uk

In article <[e-mail]>, [e-mail] (Pete Forman) writes:
|> >>>>> "Andreas" == Andreas Schwab <[e-mail]> writes:
|> >>>>> "Mark" == Mark Brader <[e-mail]> writes:
|>
|>     Mark>    #if LONG_MAX * DBL_EPSILON > 1
|>
|>     Andreas> This doesn't work as floating point numbers aren't
|>     Andreas> allowed in #if expressions.
|>
|> Try changing to something like
|>
|>     #if LONG_MAX >> DBL_MANT_DIG > 1

Don't bother - the 'constants' in <float.h> aren't!  This is a specific
exclusion to make life easier for systems with separate floating-point
processors, and makes <float.h> almost useless for numerical analysts.

I tried to get this imbecility (and it IS an imbecility) fixed, but I
failed.  So any portable library of mathematical functions has to define
its own system-dependent constants, and can use <float.h> only for
comparison :-(


Nick Maclaren,
University of Cambridge Computer Laboratory,
New Museums Site, Pembroke Street, Cambridge CB2 3QG, England.
Email:  [e-mail]
Tel.:  [phone]    Fax:  [phone]