Calc is a desk calculator utility that operates on
construc-
tive real numbers. The underlying idea is to represent a
real number as a function, to a level of accuracy specified
by the user. The results displayed by the calculator are
always accurate to the desired precision, no matter how they
were derived. The expression ln((1+e**(-500))-1) correctly
evaluates to -500.
Uses/Advantages:
The results displayed by the calculator are
always accurate to the desired precision, no matter how they
were derived. Performs
demand-driven evaluation. It allows you to scroll through results,
evaluating more digits as needed.
Version:
2.9
Catalog #:
PD95021
Platforms:
Sun Architecture
License:
Copyright 1988, 1989 Hans-J. Boehm, Vernon Lee, Alan J.
Demers
Copyright Digital Equipment Corporation & INRIA 1988, 1989
Copyright (c) 1990, 1991 by Xerox Corporation. All rights reserved.
THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
Permission is hereby granted to copy this compiler for any non-commercial
purpose, provided the above notices are retained on all copies. Further
restrictions apply to the DEC/INRIA BigNum package. These are stated in
the file runtime/BigNum/doc/bnbody.tex.
This work uses the BigNum package developed jointly by INRIA and
Digital PRL. It has been modified by Hans-J. Boehm in August 1990
at Xerox PARC. When you receive this software, please send mail to
librarian@prl.dec.com to inform them that you have a copy of the
package.
The underlying idea is to represent a real number as
a
function from a precisions specification to an approximation accurate to
the indicated precision. For efficiency reasons, these functions
"remember"
the best known approximation to a number. More details on the ideas
underlying the implementation can be found in:
Hans-J. Boehm, "Constructive Real Interpretation of Numerical Programs",
Proceedings of the SIGPLAN '87 Symposium on Interpreters and Interpretive
Techniques, SIGPLAN Notices 22, 7 (July 1987), pp. 241-221.
Hans-J. Boehm, R. Cartwright, Michael J. O'Donnell, and Mark Riggle,
"Exact Real Arithmetic: A Case Study in Higher Order Programming",
Proceedings of the 1986 Lisp and Functional Programming Conference,
pp. 162-173.
The implementation makes use of some of the algorithms used in Brent's
multiple precision package. These are described in:
Brent, R.P., "Fast Multiple-Precision Evaluation of Elementary
Functions",
Journal of the ACM 23, (1976), pp. 242-251.
The underlying constructive real package, as well as the desk
calculator
interface to it, are written in the programming language Russell. A
Russell
compiler along with source for the constructive reals package is
available
by ftp from arisia.xerox.com. If you are interested, please send mail to
boehm@xerox.com.
