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From: howard@cpocd2.UUCP
Newsgroups: comp.lang.c
Subject: Re: Order of evaluation, machine floating point
Message-ID: <521@cpocd2.UUCP>
Date: Mon, 23-Mar-87 15:08:12 EST
Article-I.D.: cpocd2.521
Posted: Mon Mar 23 15:08:12 1987
Date-Received: Wed, 25-Mar-87 06:22:05 EST
References: <4775@brl-adm.ARPA> <7779@utzoo.UUCP>
Reply-To: howard@cpocd2.UUCP (Howard A. Landman)
Organization: Intel Corp. ASIC Services Organization, Chandler AZ
Lines: 19

In article <7779@utzoo.UUCP> henry@utzoo.UUCP (Henry Spencer) writes:
>> ... for unknown reasons all floating arithmetic is supposed to occur in
>> double precision.  I realize that K&R said it, but I don't know why...
>
>Dennis Ritchie answered this on the net a long time ago:
>
>> 3) Because it is numerically more desirable to evaluate single-precision
>>    expressions in double precision, then truncate the result.
>
>#3 is usually true for the naive but makes the pros very unhappy.

Unless you happen to be working on an IBM 360/370 family machine.  The
"single precision" arithmetic is so bad that it has often been called
"half precision".  The C insistance on double precision makes a lot of
sense in such an environment.
-- 

	Howard A. Landman
	...!intelca!mipos3!cpocd2!howard