Constructive Reals Calculator
This is a modified version of the constructive reals calculator
developed by Hans-J. Boehm at SGI. The copyright for much of the code
belongs to SGI.
Since it appears to no longer be available on the SGI site, it was rehosted
here, as allowed by its license.
To run the calculator, try one of the following:
(These all run the same class files; only the parameters vary.)
This is a calculator that operates on constructive real numbers.
Numbers are represented exactly internally to the calculator, and then
evaluated on demand to guarantee an error in the displayed result that
is strictly less than one in the least significant displayed digit.
It is possible to scroll the display to the right to generate
essentially arbitrary precision in the result.
The preferred version of the calculator uses reverse Polish notation.
To add 1 and 2, either
click <1><enter><2><+> on the calculator keypad,
or click on the
display, so that it receives keyboard input, and type 1<space>2+
on the keyboard. For more detailed instructions, click
Try ePI · sqrt(163),
entered as 163 <sqrt> <pi> <*> <exp> .
To demonstrate the effect of demand-driven evaluation, try
123 <+/-> <exp> <pi> <+> <ln> <exp>
<pi> <-> <ln>.
10 <enter> 25 <^> <atan> <tan>
The calculator is implemented on top of a Java library that implements
constructive real arithmetic.
The library will live in com.hp.creals.
It provides two interesting classes:
CR provides constructive reals as a subclass
of Number. Its implementation is
provides some limited operations
on unary functions over the constructive reals. It also provides a large
number of constants for commonly used functions.
Its implementation is
Some general information on the implementation is here.
The entire calculator can be downloaded as a compressed tar file
This version of
the calculator and library code is copyrighted by Silicon Graphics, Inc.
and by Hewlett-Packard Company.
It may be used and redistributed subject to conditions specified
here and in the source files.
Please send bug reports, comments, or questions to
Hans Boehm's home page.