Maintained at https://github.com/vancegroup/EigenArduino by Ryan Pavlik - rpavlik@iastate.edu rpavlik@acm.org
The Eigen C++ template matrix/vector math library is great: simple syntax, that through the power of expression templates, compiles to code rivalling the speed of Fortran.
Sometimes you need to do a little matrix math on a microcontroller. I don't like to reinvent the wheel, nor do I find extracting the C-style math routines from some existing open-source Arduino code particularly appealing. I'd much rather use what I know works and what I already use on the desktop.
Thus, Eigen for Arduino/AVR. Yes, it works, and it's lovely.
This branch (Eigen30) contains a lightly-modified version of Eigen
3.0.6. Importantly, it includes a header to both indicate to the Arduino
IDE that this library should be used, and set up the preprocessor
environment so the ample #define lines in the Arduino and AVR
libraries don't wreak havoc with Eigen.
The avr-gcc toolchain, while capable of compiling C++, doesn't include a C++ standard library implementation. Thus, you'll have to provide your own. I've worked with the following two:
-
stlport-avr - This is what is most frequently used/tested with EigenArduino: it's based on a complete, widely-used, liberally-licensed standard library implementation (STLport - which contrary to popular belief, hasn't sat dormant since the last tagged release in 2008 - see the STLport git repo for ample signs of life). If you can control your compiler flags and use a new enough GCC, you can even use the C++11 version of STLport (master/pre-6.0). As it's just a branch of the main STLport repo, with an "Arduino-compatible" installed branch updated with an included build script, keeping in sync with upstream improvements is simple. The main drawback to using this as your C++ standard library on AVR is that iostreams won't work: They're highly dependent on locale support, and I haven't yet figured out a good way to fake/disable that.
-
StandardCplusplus - This is a more minimal, but also more incomplete library, based on the LGPL v2.1+ uClibc++ library with added (MIT-licensed) headers for Arduino stream and std::iostream interaction from Andy Brown's SGI STL port. This is actually my fork of the initial StandardCplusplus project. That initial version, like upstream uClibc++, lacked implementations for some important headers used by Eigen (such as
<limits>!), hence the need for modifications. I do think it works (as in builds) now with Eigen, but I'm not tremendously confident that my additions are correct or complete. As it is a distinct repository from the uClibc++ it was based on, investigating changes and keeping in sync with upstream is a challenge. (I did a merge once, but it wasn't fun.) The advantage to this library is that it does contain iostream support that works. It also claims to be modified to improve embedded performance, though I have done no empirical testing to support or refute this.
Clone, add as submodule, or download and unzip the desired branch of this repository inside your Arduino "libraries" directory, named to match the branch name. (If you need more detail, see [my instructions with screenshots][stlport-wiki] for doing this with STLport-avr, it's essentially the same, only the names are changed.)
Add includes to the compatibility headers for your standard C++ library and this library, in that order. For example:
#include <stlport.h>
#include <Eigen30.h>The compatibility header has included <Eigen/Core> for you. Enjoy the
functionality. You may now also include any of the other Eigen headers
using the same way you'd include them in a standard desktop system:
<Eigen/Geometry>, etc.
If you find this useful, we would appreciate hearing from you. If you use this for academic work, we would also appreciate a copy of the publication and a citation: this helps make a case for our work. You may contact the main developer, Ryan Pavlik (Iowa State University), by email at rpavlik@iastate.edu or abiryan@ryand.net, or his advisor, Dr. Judy M. Vance.
Paper materials and copies of publications may be mailed to:
Ryan Pavlik or Dr. Judy M. Vance
Virtual Reality Applications Center
1620 Howe Hall
Ames, Iowa 50011-2274
USA
The compatibility header in the main directory may be used according to these terms:
Copyright Iowa State University 2012.
Distributed under the Boost Software License, Version 1.0.
(See copy at http://www.boost.org/LICENSE_1_0.txt)
Alternately, at your option, it may be used according to the license of the Eigen version that it accompanies.
The 3.0 branch of Eigen is licensed under the LGPL3+ or GPL2+ at your option. The developers' interpretation, with support from the FSF, can be found here: http://eigen.tuxfamily.org/index.php?title=Licensing_FAQ&oldid=1117 (Version 3.1.1 and newer have switch to the MPL v2 which better expresses the developers' intent.)