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From: dewar@merv.cs.nyu.edu (Robert Dewar)
Subject: Re: Fixed-point
Date: 1997/03/28
Message-ID: <dewar.859584171@merv>#1/1
X-Deja-AN: 229129935
References: <333C08A7.446B9B3D@innocon.com>
Organization: New York University
Newsgroups: comp.lang.ada
Date: 1997-03-28T00:00:00+00:00
List-Id: <comp.lang.ada>


Jeff Carter asks

<<Jack Crenshaw's "Programmer's Toolbox" column in *Embedded Systems
Programming* has been discussing implementing multiple precision
integers and fixed-point types in C++ for some time. I was wondering
when he'd address why you'd go to the effort, rather than use a language
with fixed-point type support. In the 1997 Apr issue, he does:

"The designers of Ada ... tried to get too fancy. Instead of restricting
the type to words commensurate with the natural word length of the
computer, they gave us a more general definition that allows for words
of any bit length and any resolution. ... [T]he end result was the same:
fixed-point operations are so slow in Ada that few people bother to use
the type, and many Ada shops prohibit their use as a matter programming
style."

Has anyone encountered this phenomenon?>>


Robet replies

I doubt anyone has "encountered this phenomenon" since the quotation
is complete nonsense, and shows that the author knows nothing about
fixed-point in Ada. There are some problems with fixed-point, especially
in Ada 83, but they are essenti9ally fixed in Ada 95. For a detailed
discussion of these problems, see my repot on fixed-point, this was
one of the SEI reports done for the Ada 9X development effort.