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From: manis@ubc-cs.UUCP (Vincent Manis)
Newsgroups: comp.sys.atari.st
Subject: Re: More ST Floating Point Performance - (nf)
Message-ID: <1488@ubc-cs.UUCP>
Date: Mon, 22-Jun-87 20:26:23 EDT
Article-I.D.: ubc-cs.1488
Posted: Mon Jun 22 20:26:23 1987
Date-Received: Wed, 24-Jun-87 03:15:45 EDT
References: <1959@trwrb.UUCP> <19400004@qtecmuc.UUCP>
Reply-To: manis@ubc-cs.UUCP (Vincent Manis)
Organization: UBC Department of Computer Science
Lines: 30

In article <19400004@qtecmuc.UUCP> ger@qtecmuc.UUCP writes:

>According to Kernighan&Ritchie (Appendix A, 6.2 on page 184 in my copy)
>'all floating point arithmetic in C is carried out in double
>precision'.  Therefore, if manx on the AMIGA really uses one longword
>for floating point evaluations it simply isn't real C and benchmarks
>with this compiler are pure nonsens if compared with 'correct'
>C-Compilers using 64bit double precision.

Yet another instance where K&R are incorrect. When they say "double
precision" they really mean type "double", which may or may not actually be
double precision.  An Amiga implementation which treats float and double the
same is not incorrect (though obviously not as good as one which provides
extra precision). ANSI says that double can have no less precision than
float, which the Lattice version certainly satisfies.

Incidentally, I goofed in a recent posting on Mark Williams C f.p. I said
that they implement the VAX F and D formats (found on the PDP-11). Looking
at the MWC manual, it appears that they use VAX G format (slightly more
exponent, slightly less fraction. 

-----
Vincent Manis                {seismo,uw-beaver}!ubc-vision!ubc-cs!manis
Dept. of Computer Science    manis@cs.ubc.cdn
Univ. of British Columbia    manis%ubc.csnet@csnet-relay.arpa  
Vancouver, B.C. V6T 1W5      manis@ubc.csnet
(604) 228-6770 or 228-3061

"To lose one parent, Mr Worthing, may be regarded as a misfortune; but
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