Nengo-loihi

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

*Compatible with NxSDK 0.7.0 - 0.8.0*

**Changed**

- New Nengo transforms are supported, including ``nengo.Convolution``. Many of
the classes previously in ``conv.py`` have been moved to Nengo as part of
this transition. The MNIST convnet example demonstrates the new syntax.
(`142 <https://github.com/nengo/nengo-loihi/pull/142>`__)
- Emulator now fails for any cx_base < 0, except -1 which indicates
an unused axon.
(`185 <https://github.com/nengo/nengo-loihi/pull/185>`__)
- Noise now works correctly with small exponents on both the chip and
emulator. Previously, the emulator did not allow very small exponents, and
such exponents produced noise with the wrong magnitude on the chip.
(`185 <https://github.com/nengo/nengo-loihi/pull/185>`__)
- Models trained using NengoDL use tuning curves more similar to those
of neuron on the chip, improving the accuracy of these model.
(`140 <https://github.com/nengo/nengo-loihi/pull/140>`__)

**Removed**

- Removed the ``NIF`` and ``NIFRate`` neuron types. These types were only used
for encoding node values in spikes to send to the chip, which can be done
just as well with ``nengo.SpikingRectifiedLinear`` neurons.
(`185 <https://github.com/nengo/nengo-loihi/pull/185>`__)
- Removed the unused/untested ``Synapse.set_diagonal_weights``.
(`185 <https://github.com/nengo/nengo-loihi/pull/185>`__)

**Fixed**

- Objects in nengo-loihi will have the same random seeds as in
nengo core (and therefore any randomly generated parameters, such as
ensemble encoders, will be generated in the same way).
(`70 <https://github.com/nengo/nengo-loihi/pull/70>`_)
- Seeded networks that have learning are now deterministic on both
emulator and hardware.
(`140 <https://github.com/nengo/nengo-loihi/pull/140>`__)

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

*Compatible with NxSDK 0.7.0 - 0.8.0*

**Added**

- Allow ``LIF.min_voltage`` to have effect. The exact minimum voltage on the
chip is highly affected by discritization (since the chip only allows
minimum voltages in powers of two), but this will at least provide something
in the ballpark.
(`169 <https://github.com/nengo/nengo-loihi/pull/169>`__)
- Population spikes can now be used to send information more efficiently
to the chip. Population spikes are necessary for larger models
like those using CIFAR-10 data.
(`161 <https://github.com/nengo/nengo-loihi/pull/161>`__)

**Changed**

- PES learning in Nengo Loihi more closely matches learning in core Nengo.
(`139 <https://github.com/nengo/nengo-loihi/pull/139>`__)
- Learning in the emulator more closely matches learning on hardware.
(`139 <https://github.com/nengo/nengo-loihi/pull/139>`__)
- The neurons used to transmit decoded values on-chip can be configured.
By default, we use ten pairs of heterogeneous neurons per dimension.
(`132 <https://github.com/nengo/nengo-loihi/pull/132>`_)
- Internal classes and functions have been reorganized and refactored.
See the pull request for more details.
(`159 <https://github.com/nengo/nengo-loihi/pull/159>`_)
- Simulator now gives a warning if the user requests a progress bar, instead
of an error. This avoids potential problems in ``nengo_gui`` and elsewhere.
(`187 <https://github.com/nengo/nengo-loihi/pull/187>`_)
- Nengo Loihi now supports NxSDK version 0.8.0.
Versions 0.7.0 and 0.7.5 are still supported.
(`188 <https://github.com/nengo/nengo-loihi/pull/188>`__)

**Fixed**

- We integrate current (U) and voltage (V) more accurately now by accounting
for rounding during the decay process. This integral is used when
discretizing weights and firing thresholds. This change significantly
improves accuracy for many networks, but in particular dynamical systems
like integrators.
(`124 <https://github.com/nengo/nengo-loihi/pull/124>`_,
`114 <https://github.com/nengo/nengo-loihi/issues/114>`_)
- Ensure things in the build and execution happen in a consistent order from
one build/run to the next (by using ``OrderedDict``, which is deterministic,
instead of ``dict``, which is not). This makes debugging easier and seeding
consistent.
(`151 <https://github.com/nengo/nengo-loihi/pull/151>`_)
- Probes that use snips on the chip (when running with ``precompute=False``)
now deal with negative values correctly.
(`169 <https://github.com/nengo/nengo-loihi/pull/124>`_,
`141 <https://github.com/nengo/nengo-loihi/issues/141>`_)
- Filtering for probes on the chip
is guaranteed to use floating-point now (so that the filtered output
is correct, even if the underlying values are integers).
(`169 <https://github.com/nengo/nengo-loihi/pull/124>`_,
`141 <https://github.com/nengo/nengo-loihi/issues/141>`_)
- Neuron (spike) probes can now be filtered with ``synapse`` objects.
(`182 <https://github.com/nengo/nengo-loihi/issues/182>`__,
`183 <https://github.com/nengo/nengo-loihi/pull/180>`__)

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

*Compatible with NxSDK 0.7.0*

**Added**

- Added version tracking to documentation.

**Changed**

- An error is now raised if
a learning rule is applied to a non-decoded connection.
(`103 <https://github.com/nengo/nengo-loihi/pull/103>`_)
- Switched documentation to new
`nengo-sphinx-theme <https://github.com/nengo/nengo-sphinx-theme>`_.
(`143 <https://github.com/nengo/nengo-loihi/pull/143>`__)

**Fixed**

- Snips directory included when pip installing nengo-loihi.
(`134 <https://github.com/nengo/nengo-loihi/pull/134>`__)
- Closing ``nengo_loihi.Simulator`` will now close all the inner
sub-simulators as well.
(`102 <https://github.com/nengo/nengo-loihi/issues/102>`_)

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

*Compatible with NxSDK 0.7.0*

**Added**

- Models can now use the ``nengo.SpikingRectifiedLinear`` neuron model
on both the emulator and hardware backends.
- Models can now run with different ``dt`` values
(the default is 0.001, or 1 millisecond).
- Added support for Distributions on Connection transforms.

**Changed**

- Now compatible with NxSDK 0.7. We are currently not supporting
older versions of NxSDK, but may in the future.
- Models will not be precomputed by default. To precompute models,
you must explicitly pass ``precompute=True`` to ``nengo_loihi.Simulator``.
- Models that do not run any objects on Loihi will raise an error.
- Ensemble intercept values are capped to 0.95 to fix issues with
the current discretization method.

**Fixed**

- Tuning curves now take into account the Loihi discretization,
improving accuracy on most models.
- PES learning can now be done with multidimensional error signals.
- Manually reset spike probes when Simulator is initialized.
- Several fixes to filtering and connecting
between objects on and off chip.

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

First public alpha release of Nengo Loihi!
If you have any questions,
please `ask on our forum <https://forum.nengo.ai/c/backends/loihi>`_
and if you run into any issues
`let us know <https://github.com/nengo/nengo-loihi/issues>`_.

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

Pre-alpha release of Nengo Loihi for testing at the
2018 Telluride neuromorphic engineering conference.
Thanks to all participants who tried out
this early version of Nengo Loihi
and provided feedback.