Nengo-spa

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

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

**Changed**

- Made NengoSPA available under the GPLv2 license.
(`295 <https://github.com/nengo/nengo-spa/pull/295>`__)

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

**Added**

- Support for (fractional) binding powers and the notion of signs in algebras
and for `SemanticPointer` instances.
(`271 <https://github.com/nengo/nengo_spa/pull/271>`__,
`286 <https://github.com/nengo/nengo_spa/pull/286>`__)
- ``EquallySpacedPositiveUnitaryHrrVectors`` and ``VectorsWithProperties``
vector generators.
(`284 <https://github.com/nengo/nengo_spa/issues/284>`__,
`285 <https://github.com/nengo/nengo_spa/pull/285>`__)
- Example of how to use learning connections between ``State`` modules.
(`16 <https://github.com/nengo/nengo_spa/issues/16>`__,
`288 <https://github.com/nengo/nengo_spa/pull/288>`__)

**Removed**

- Python 3.5 support was removed.
(`273 <https://github.com/nengo/nengo_spa/issues/273>`__,
`274 <https://github.com/nengo/nengo_spa/pull/274>`__)

**Fixed**

- Scalar arrays like ``np.array(1)`` will now be treated as scalars as intended.
(`289 <https://github.com/nengo/nengo_spa/pull/289>`__)

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

**Added**

- Transposed Vector-derived Transformation Binding (TVTB) algebra which has
essentially the same properties as the existing VTB algebra, but has two-sided
identities and inverses (opposed to VTB where these are right-sided only).
The only difference in the math is that TVTB transposes the matrix used in the
binding operation.
(`266 <https://github.com/nengo/nengo_spa/issues/266>`__)
- Differentiation between left, right, and two-sided special elements (identity,
zero, absorbing element, inverse) of an algebra.
(`265 <https://github.com/nengo/nengo_spa/pull/265>`__)
- Added ``linv`` and ``rinv`` methods to ``SemanticPointer`` for the left and
right inverse, respectively.
(`265 <https://github.com/nengo/nengo_spa/pull/265>`__)
- Add support for the ``normalized`` and ``unitary`` methods on Semantic Pointer
symbols.
(`265 <https://github.com/nengo/nengo_spa/pull/265>`__)

**Changed**

- Creating special elements (identity, zero, absorbing element, inverse) of the
``VtbAlgebra`` without ``sidedness`` argument has been deprecated because
these are only right-sided special element. Add the
``sidedness=ElementSidedness.RIGHT`` argument to update your code.
(`265 <https://github.com/nengo/nengo_spa/pull/265>`__)
- The ``~`` operator has been deprecated for the ``VtbAlgebra``. Use the
``rinv()`` method instead.
(`265 <https://github.com/nengo/nengo_spa/pull/265>`__)
- Improved automatic names for ``SemanticPointer`` that only contain parenthesis
where actually needed. In addition, syntax is considered when shortening a
name exceeding the maximum length.
(`255 <https://github.com/nengo/nengo_spa/issues/255>`__,
`270 <https://github.com/nengo/nengo_spa/pull/270>`__)

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

**Fixed**

- ``PointerSymbol`` precedence handling has been fixed. For example,
``(sym.A + sym.B) * sym.C`` will be evaluated correctly now.
(`267 <https://github.com/nengo/nengo_spa/issues/267>`__,
`268 <https://github.com/nengo/nengo_spa/pull/268>`__)

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

**Added**

- Support division with constant scalars.
(`249 <https://github.com/nengo/nengo_spa/issues/249>`__,
`253 <https://github.com/nengo/nengo_spa/pull/253>`__,
`257 <https://github.com/nengo/nengo_spa/pull/257>`__)

**Changed**

- Make ``AbstractAlgebra`` an actual abstract base class (using ``ABCMeta`` as
meta-class). While still supported, this deprecates pure duck-typing for
algebras.
(`240 <https://github.com/nengo/nengo_spa/pull/240>`__)
- Raise an exception when a Semantic Pointer is added to a vocabulary with a
differing algebra.
(`239 <https://github.com/nengo/nengo_spa/issues/239>`__,
`240 <https://github.com/nengo/nengo_spa/pull/240>`__)
- All examples now have seeds to ensure that occasional "bad seeds" do not create
problems in the documentation.
(`248 <https://github.com/nengo/nengo_spa/pull/248>`__)

**Fixed**

- ``SemanticPointer.translate`` and ``PointerSymbol.translate`` now use the ``keys``
argument; previously, this argument was mistakenly ignored.
(`248 <https://github.com/nengo/nengo_spa/pull/248>`__)
- Fixed an issue where the names of iteratively generated semantic pointers
could grow exponentially in length, by truncating them at 1 KB.
(`244 <https://github.com/nengo/nengo_spa/issues/244>`__,
`246 <https://github.com/nengo/nengo_spa/pull/246>`__)
- Allow NumPy scalars in place of Python scalars for binary operations on
`SemanticPointer` instances.
(`250 <https://github.com/nengo/nengo_spa/issues/250>`__,
`257 <https://github.com/nengo/nengo_spa/pull/257>`__)
- The SPA sequence example was not working properly due to a missing connection.
(`258 <https://github.com/nengo/nengo_spa/issues/258>`__,
`259 <https://github.com/nengo/nengo_spa/pull/259>`__)