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From: ali@rocky.STANFORD.EDU (Ali Ozer)
Newsgroups: comp.sys.atari.st
Subject: Re: More ST Floating Point Performance - (nf)
Message-ID: <371@rocky.STANFORD.EDU>
Date: Sun, 21-Jun-87 17:02:19 EDT
Article-I.D.: rocky.371
Posted: Sun Jun 21 17:02:19 1987
Date-Received: Tue, 23-Jun-87 01:32:16 EDT
References: <1959@trwrb.UUCP> <19400004@qtecmuc.UUCP>
Reply-To: ali@rocky.UUCP (Ali Ozer)
Distribution: world
Organization: Stanford University Computer Science Department
Lines: 19

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.

The use of single-word floating point operations is a feature, not a 
limitation. Manx gives you various FP modes, among which the IEEE double
and the Motorola FFP. 68881 is also supported. You specify which mode you
want through switches to the compiler and/or linking in the various
libraries...

Now if I have a program that did not need 10+ digits but could get away with
the 7 or so digits Motorola FFP provides, I will certainly use the FFP mode,
considering it is 7 to 8 times faster. 

Ali Ozer, ali@rocky.stanford.edu