Decimal Floating types was RE: Information Systems Annex was RE: Dispatching and generics - language lawyer question

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

From: Bob Leif
To: Robert Dewar et al.

Please see IBM http://www2.hursley.ibm.com/decimal/
"Standard Decimal Arithmetic"

"Most computers today support binary floating-point in hardware. While
suitable for many purposes, binary floating-point should not be used for
financial, commercial, and user-centric applications and web services
because the decimal data used in these applications cannot be
represented exactly using binary floating-point. (See the Frequently
Asked Questions page for more reasons and examples.) "

"The problems of binary floating-point can be avoided by using base 10
(decimal) exponents and preserving those exponents where possible. This
site describes a decimal arithmetic which achieves the necessary results
and conforms to the relevant ANSI and IEEE standards. Notably, a single
data type can be used for integer, fixed-point, and floating-point
decimal arithmetic."


Since COBOL does not have a decimal floating point, COBOL programmers,
who still do most of the financial applications, have not had a chance
to try it!.  There is another class of financial programmers, the Wall
Street analysts. The analysts do derivatives and other exotic financial
instruments. Do they use conventional binary floating point or COBOL
decimal? 

I might note that you have in the past quite properly cautioned on the
complexity of conventional floating point calculations. One good way to
check them would be to employ a decimal floating point.

On a philosophical level, since computers are supposed to work for
humans, why not have them work in the most understandable way? I would
greatly prefer my spreadsheets and computer assisted mechanical design
programs be in decimal. Humans work in pseudo-integer space. We like our
numbers and dimensions, in particular, to be a float that corresponds to
an integer followed by a decimal point, followed by zeros. Designers do
not like to fiddle with a dimension that comes out 28.998. We greatly
prefer 29.000.



-----Original Message-----
From: comp.lang.ada-admin@ada.eu.org
[mailto:comp.lang.ada-admin@ada.eu.org] On Behalf Of Robert Dewar
Sent: Thursday, August 15, 2002 2:27 AM
To: comp.lang.ada@ada.eu.org
Subject: Re: Information Systems Annex was RE: Dispatching and generics
- language lawyer question

"Robert C. Leif" <rleif@rleif.com> wrote in message
news:<mailman.1029282844.28090.comp.lang.ada@ada.eu.org>...
> Ada decimal types (as currently defined) are fixed-point
> types.
> 
> Are you asking for decimal floating-point?


Decimal floating-point would be quite useless in financial
applications as far as I can see (COBOL does not have this
facility). What you need in financial calculations is decimal
fixed-point, and very occasionally (this has only
recently been included in the COBOL standard) binary fpt.