A newer, somewhat experimental, version of this calculator can
be found here.
This is a slightly modified version of the constructive reals calculator
developed by Hans-J. Boehm at SGI. The copyright belongs to SGI.
Since it appears to no longer be available on the SGI site, it was rehosted
here, as allowed by its license.
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 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
The calculator is implemented on top of a Java library that implements
constructive real arithmetic.
The library will live in com.sgi.math.
It provides two interesting classes:
CR provides constructive reals as a subclass
of Number. Its interface is described
provides some limited operations
on unary functions over the constructive reals. It also provides a large
number of constants for commonly used functions.
Its interface is described
Some general information on the implementation is here.
The entire calculator can be downloaded as a compressed tar file
The calculator and library code is copyrighted by Silicon Graphics, Inc.
It may be used and redistributed subject to conditions specified
here and in the source files.