The Light Efficient Network Simulator (LENS) was originally written by Douglas Rhode, copyright 1998-2004. Prior to this repo, the last "stable" release was version 2.64-cnbc.1, hosted at Stanford University at http://web.stanford.edu/group/mbc/LENSManual/. This release was still being built against Tcl/Tk 8.3, and was a challenge to build on modern systems.

The source code in this repo has been updated to build against Tcl/Tk 8.6.4. It has been tested on:

• Ubuntu 14.04 (trusty) 64-bit.
• Ubuntu 15.10 (Wily) 64-bit.
• Scientific Linux 6 64-bit.

git clone https://github.com/crcox/lens.git

Should do the trick. If you are using the Manchester CSF, note that git seems to only work on the scratch/ filesystem, and not in the ${HOME} directory.

The build process is laid out in compile.sh. If you are using the Manchester CSF, the build process is scripted in csf-build-lens.sh. Just run

mkdir csf-build-lens-logfiles # first build only
qsub csf-build-lens.sh

First, decide on where you want Tcl/Tk to be installed. To be super-safe, the following instructions demonstrate making a completely new (and isolated) installation location. If you want other software to use Tcl/Tk, you might install to a more central location.

TOP=$(pwd)
# This directory is where the Tcl/Tk libraries will be installed to. If
# you have a prefered location for installations, go ahead and use that.
export PREFIX=${TOP}/usr/local
mkdir -p ${PREFIX}

Then, build Tcl:

# Compile Tcl
cd "TclTk/tcl8.6.4/unix"
./configure --enable-shared --prefix=${PREFIX} && make && make install

Then, build Tk:

# Compile Tk
cd "../../tk8.6.4/unix"
./configure --enable-shared --prefix=${PREFIX} --with-tcl=../../tcl8.6.4/unix/ && make && make install

Finally, build Lens:

# Compile Lens
cd ${TOP}
export CFLAGS="-I${PREFIX}/include"
export LDFLAGS="-L${PREFIX}/lib -L${PREFIX}/lib/tcl8.6 -L${PREFIX}/lib/tk8.6"
# I need up tweak the Makefile so this works properly...
# export LD_RUN_PATH="${PREFIX}/lib:${PREFIX}/lib/tcl8.6:${PREFIX}/lib/tk8.6"
make

For Lens to run, some environment variables need to be set. If you are running Lens on a distributed cluster, run_Lens.sh will handle setting up the environment on the remote machine.

The spirit of the instructions at http://web.stanford.edu/group/mbc/LENSManual/Manual/running.html still apply to setting up your environment to run Lens, with slight differences. The following instructions will work with bash or zsh.

First, set the LENSDIR environment variable.

# Your LENSDIR will probably be $TOP, created at the start of the build process.
export LENSDIR=<your Lens directory>

Next, you need to let Lens/your system know where to find the Tcl/Tk libraries we compiled. Add this location to your LD_LIBRARY_PATH environment variable.

export LD_LIBRARY_PATH=${LD_LIBRARY_PATH}:${PREFIX}/lib

Finally, you need to let your system know where the the Lens executable is on your system. Note that the build process did not install Lens anywhere other than ${LENSDIR}/Bin. So, you need to add that to the system path:

export PATH=${PATH}:${LENSDIR}/Bin

You might add all of these export commands to your ${HOME}/.bashrc (or .zshrc, as the case may be). Equivalent commands are different in other shells, so you may need to Google to make this work with your shell of choice.

Running Lens on the CSF is actually very easy once it is compiled and your environment is set propperly, as described above. Try running:

qsub csf-example-lens.sh

After a couple seconds, there should be log files in the csf-build-lens-logfiles directory. Once that is working, you can experiment with writing out weight files and activation states as needed, using csf-example-lens.sh and Examples/digits_autorun.in as jumping off points.

LENS is a neural network simulator written specifically for cognitive science, and so has many features that more generic packages do not have. It is also lightweight, and can be run in batch mode without ever loading a GUI. This is useful when scaling up or when running many iterations of a simulation in a distributed computing environment. It is written to be extensible. The LENS is (Tcl) script driven, and so you have a great deal of flexibility without needing to write a new C extension.

I am working on this revitilization of LENS because I see a pressing need for it. However, there are many things that I am learning as I go in order to do so---this is my first project in C, and by extension using the Tcl API. I have never written a make file, and know very little about configuration and build tools. I am excited to learn, but also very much looking for help even on things that strike you as trivial, because it's probably not trivial from where I am sitting.