Frequently Asked Questions

1. Download Nengo
2. Unzip it and run nengo on Mac OS X or Linux, or nengo.bat on Windows
3. Follow this tutorial

The main difference is in how the connection strengths between neurons are specified. For other neural simulators, you either set these weights manually or you set them randomly and specify a learning rule. Nengo allows you to specify the overall function that should be computed, and then it will solve for the connection weights that will best approximate that function. This allows the model designer to work at a higher level of abstraction (vectors and functions) and yet still produce a detailed model using realistic spiking neurons. You can use the other methods to specify and/or adapt weights as well.

Yes. Nengo can use any sort of neuron model, including the common non-spiking rate neuron models. Indeed, you can even change from spiking neurons to rate neurons in the middle of a simulation, or have a mixture of spiking and rate neurons in your model. Nengo also supports various learning rules. You can also manually specify connection weights, if desired.

Many example functions can be found in the "demo" directory of a standard Nengo install. They are explained in the documentation, and many are explained in the videos. You can also look through the Nengo Model Archive to find examples.

Yes. See the various scripts in the demos and videos section of this website with 'learning' in the title. Several papers in the CNRG Publications section also discuss learning in some detail. Such as this one, and this one.

You can define any connection weights you like using the built-in scripting language. Instructions and examples can be found here.

Right-click the background and select 'zoom to fit'.

You should be able to eliminate the problems by unchecking the scroll button for one-finger in the OS X Mouse Preferences.

This video or this more advanced one, or the tutorials are the best places to start.

If you right click on any input slider, you can select the option to load a .csv file. The first column is the time, and the remaining columns define the values of the various input dimensions at those times. This can be saved/edited as an excel file.

You can save all of the generated data by opening the settings (at the bottom), and clicking the page-like icon. The screen that is shown displays all of the decoded values by default. Right-clicking allows you to choose other data to display. The data is saved to a .csv file by clicking on the disk icon on this screen.

Yes. In the settings menu at the bottom of the page, press the .pdf logo and a save file box will appear. This is a vectorized version of the current display.

A: Two options. You can do it this way:

import ca.nengo.utils


but then when you use the library, you will have to provide its full name:

y=ca.nengo.utils.DataUtils.filter(x,0.005)


The other option is to import this way:

from ca.nengo.utils import *


This allows you to just do:

y=DataUtils.filter(x,0.005)


http://nengo.ca/docs/html/configuring.html#encoders-a-k-a-preferred-dire...

Nengo has a command-line version called nengo-cl. You can run a script by specifying it on the command line, such as nengo-cl myscript.py. On Linux and OS X, you may have to specify the directory the script is in, which is often done by writing ./nengo-cl myscript.py.

A: You can! For a detailed explanation, see this blog post, but all it takes is one line of code.

A plot with a ton of whitespace, specifically sized with the line

figure('Position',[0,100,700,350],'Resize','off');


The same data plotted with the following additional line right after the figure call above, will have little whitespace.

set(gca, 'Position', get(gca, 'OuterPosition') - ...
get(gca, 'TightInset') * [-3 0 3 0; 0 -3 0 4; 0 0 3 0; 0 0 0 3]);


Note that the matrix at the end of the above line can be tweaked to change the margin on each of the four sides.

A: Your best bet is http://nengo.ca/documentation. You can even download most of it as a .pdf.

A: If you have a question not answered in the documentation, please join the user's mailing list, and ask it there.