https://github.com/xman/sgpositpy

Probably correct posit prototype for python
https://github.com/xman/sgpositpy

posit python unum

Last synced: about 2 months ago
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Probably correct posit prototype for python

• Host: GitHub
• URL: https://github.com/xman/sgpositpy
• Owner: xman
• License: mit
• Created: 2018-01-05T18:53:35.000Z (almost 7 years ago)
• Default Branch: master
• Last Pushed: 2019-11-23T10:28:15.000Z (about 5 years ago)
• Last Synced: 2024-07-08T03:39:55.022Z (6 months ago)
• Topics: posit, python, unum
• Language: Python
• Homepage:
• Size: 109 KB
• Stars: 17
• Watchers: 6
• Forks: 2
• Open Issues: 5
• Metadata Files:
  • Readme: README.rst
  • License: LICENSE

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README

        
sgpositpy

=========

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Posit is a new binary format for representing decimal numbers, an alternative to

IEEE 754 floating-point number. Different configurations on the number bit size

and the scaling are possible. Details can be found at the posithub_ and the

`notebook on posit`_.

We are interested to experiment with different posit configurations the `nbits`

and the `es` sizes, and attempt to use smaller bit sizes in our applications

while achieving the required accuracy to operate. However, an implementation

conforming to the posit design is still lacking for popular programming

languages.

This project, *sgpositpy*, is our attempt to develop a prototype implementation

that is correct by the posit design. This can then serve as a reference for

subsequent development of performance optimized posit library. Hence, the

computation efficiency is currently not the focus of the project.

.. _posithub: https://posithub.org

.. _notebook on posit: https://posithub.org/docs/Posits4.pdf

Current status

==============

The current implementation is research oriented and experimental at pre-alpha stage.

This is **NOT** currently suitable for production use.

Install

=======

Install from PyPI

.. code:: bash

    $ pip install sgposit

Install from code repository

.. code:: bash

    $ git clone https://github.com/xman/sgpositpy

    $ cd sgpositpy

    $ pip install -r requirements.txt

    $ python setup.py install

    # Run regression tests.

    $ python setup.py test

    # Enable long running tests.

    $ SGPOSIT_LONG_TESTS=1 python setup.py test

Getting started

===============

The `PCPosit` class is our reference implementation with extensive regression

tests. We shall have performance optimized version in `Posit` class for general

use in the future.

The following code snippet creates posit objects from the given bit patterns,

and the posit configuration, `nbits` and `es`.

.. code:: python

    # file: samples/pcposit_sample.py

    from sgposit.pcposit import PCPosit

    a = PCPosit(0x0C, mode='bits', nbits=6, es=2)

    b = PCPosit(0x0F, mode='bits', nbits=6, es=2)

    c = a + b

    print("{} + {} => {}".format(a, b, c))

    d = a - b

    print("{} - {} => {}".format(a, b, d))

    e = a * b

    print("{} * {} => {}".format(a, b, e))

    f = a / b

    print("{} + {} => {}".format(a, b, f))

    g = -a

    print("uminus {} => {}".format(a, g))

.. code:: bash

    $ python samples/pcposit_sample.py

    1/4 + 3/4 => 1

    1/4 - 3/4 => -1/2

    1/4 * 3/4 => 3/16

    1/4 / 3/4 => 3/8

    uminus 1/4 => -1/4

License

=======

*sgpositpy* is licensed under MIT License.