RE: Floating Decimal Package/Library?

["Robert C. Leif" <rleif@rleif.com>]

From: Bob Leif
To: Waldek Hebisch et al.
The point is NOT speed but is accuracy and understandability. Our
arithmetic education is based on decimals. Fixed point types including
decimal types have the problem of not being able to create a type with
an exponent (delta) value calculated at run-time. Either a user formula
or a default to the equivalent of floating point could be used for
calculating the value of the exponent. This probably is a pain for the
compiler writers. However, one of the virtues of Ada is that the
compiler writers work to ease the developers' work. A simple example of
the use of a floating decimal type is spreadsheets, which should be
based on type decimal. 

-----Original Message-----
From: comp.lang.ada-admin@ada.eu.org
[mailto:comp.lang.ada-admin@ada.eu.org] On Behalf Of Waldek Hebisch
Sent: Wednesday, July 17, 2002 2:56 PM
To: comp.lang.ada@ada.eu.org
Subject: Re: Floating Decimal Package/Library?

Warren W. Gay VE3WWG (ve3wwg@cogeco.ca) wrote:
: Since the PostgreSQL group have expressed no
: interest in supporting floating decimal
: routines for the client, I wonder if anyone
: in these groups know of an Ada package (preferred),
: or C/C++ library that supports arbitrary
: prcecision floating decimal values. I could
: hack the PostgreSQL back end C routines, but
: this may not be practical.

: The GNU GMP library comes close, but its
: floating support library uses binary
: arithmetic (this is a no-no for financial
: work). I've suggested that they augment GMP
: with this support, but I'm not sure what
: response I'll get to the request.

: I am looking for a PD/GPL/Open Sourced work.

Well, decimal floating point is an oxymoron: floating 
point is inherently inaccurate so the representation 
does not matter. What you want is fixed point arithmetic.
Fixed point is not hard to do once you have arbitrary 
precision integers (for integers again binary versus decimal 
 does not matter). For example Tiny Cobol build all its 
decimal on top of GMP. One may be concerned with 
efficency of such implementation, but I think that 
on binary machines 20-30 digit decimal arithmetic 
cannot be really fast.




--
                              Waldek Hebisch
hebisch@math.uni.wroc.pl    or hebisch@hera.math.uni.wroc.pl