Version 16 (modified by rtoy, 3 years ago)


Welcome to Oct, a portable implementation of quad-double numbers


Oct is a portable Lisp implementation of quad-double arithmetic. This gives about 65 digits of precision. Quad-double arithmetic uses four double-float numbers to represent an extended precision number.

The implementation is modeled on the  quad-double package by  Yozo Hida. That package is in C++, but we have translated parts of it and extended it to use Lisp. The intent is to provide all of the CL arithmetic functions with a quad-double implementation.


Supported Lisps

This package has been tested with  CMUCL,  SBCL,  Clisp,  Clozure CL and  Allegro. (Allegro has not been tested recently, though). The status of these Lisps is given in the table below:

Lisp Status
CMUCL All tests pass
SBCL All tests pass
CCL All tests pass except for two, which are probably bugs in CCL
Clisp All tests pass, but clisp doesn't support signed floating-point zeros
Ecl Not working
Allegro Working, but not recently tested

Note that development is primarily done using CMUCL.

Getting Oct

Currently the only way to obtain the software is via git. You can browse the source using the  Browse Source link above, or you can use the  gitweb interface to browse the sources.

To obtain the sources, you will have to clone the repository at git:// or

Additional Information

For additional information see:

Other information can be found on the Oct project page.

Please read the TracGuide to help you get started with your project.

Also see for some information about how Trac is configured and for hints which you may be interested in.

The maintainers

Starting Points

For a complete list of local wiki pages, see TitleIndex.