[WIP] New MATLAB wrapper

[ProfFan]

We need to finish this before 4.1.

• code generation for some method signatures is broken (wrong type)
• matlab compiles (only for gtsam, gtsam_unstable is broken even in develop)
• we have not tested on MATLAB at all (I don't know how to load the module)
• resolve overloads or add numbering?
• resolve the issue where the numbering of C++ and matlab functions mismatch
• resolve the crashes on factor construction
• This declarations are broken because the concrete type is dropped during parsing

[ProfFan]

@dellaert

[ProfFan]

I have updated the feature/new_wrapper branch to reflect the changes.

[ProfFan]

I have finished the wrapping for matlab and briefly tested on MATLAB (loading and simple function works), could anyone help me test it by:

• Clone the feature/new_wrapper branch
• git submodule update --init --recursive
• mkdir build && cd build
• cmake -DCMAKE_BUILD_TYPE=Release -DGTSAM_TYPEDEF_POINTS_TO_VECTORS=ON -DGTSAM_INSTALL_MATLAB_TOOLBOX=ON -DCMAKE_INSTALL_PREFIX=../gtsam_install -DGTSAM_CUSTOM_MATLAB_PATH=<your matlab>/MATLAB/R2020a/bin ..
• make -j8 install
• Go to ../gtsam_install/gtsam_toolbox and run the matlab wrapper

And report the issues you have? Many thanks!

@varunagrawal @mikesheffler @dellaert

[ProfFan]

I am getting errors like this when running the examples:

PlanarSLAMExample
Error using gtsam.NonlinearFactorGraph
Error: File: NonlinearFactorGraph.m Line: 341 Column: 5
'push_back' is already defined as a method in the 'NonlinearFactorGraph' class.

Error in PlanarSLAMExample (line 29)
graph = NonlinearFactorGraph;

So we probably need to do some name mangling here.

[ProfFan]

Same goes for the file name resolution. Really need some help from someone with better MATLAB experience...

[varunagrawal]

I'll take a look at this later today.

[ProfFan]

@varunagrawal Thank you in advance :) I need a list of problems so I can tweak the generation code...

[ProfFan]

Another rather serious issue is that the current generator will generate identical signature for overloaded function, which is illegal in MATLAB:

    function varargout = RzRyRx(varargin)
      % RZRYRX usage: RzRyRx(double x, double y, double z) : returns gtsam::Rot3
      % Doxygen can be found at http://research.cc.gatech.edu/borg/sites/edu.borg/html/index.html
      varargout{1} = gtsam_wrapper(263, varargin{:});
    end

    function varargout = RzRyRx(varargin)
      % RZRYRX usage: RzRyRx(Vector xyz) : returns gtsam::Rot3
      % Doxygen can be found at http://research.cc.gatech.edu/borg/sites/edu.borg/html/index.html
      varargout{1} = gtsam_wrapper(264, varargin{:});
    end

[ProfFan]

Now most of the API is working, but construction of a simple factor crashes MATLAB:

import gtsam.*

graph = NonlinearFactorGraph;

%% Add prior
priorNoise = noiseModel.Diagonal.Sigmas([0.3; 0.3; 0.1]);
graph.add(PriorFactorPose2(1, Pose2(0, 0, 0), priorNoise)); % Crashes here

I'll keep investigating what is happening, but any help is welcome...

[dellaert]

I'm puzzled because many of these issues were not present for the c++ based wrap, and I thought we generated nearly identical c++ wrapper files. So, what's up with that? Let's talk in our meeting.

[ProfFan]

@dellaert Sure, it's a lot of delicate name mangling differences....

[ProfFan]

Now the crash is fixed and the examples mostly work.

[ProfFan]

Since 4.0.3 is out, we now need testers for the new MATLAB wrapper, since the generated code currently does not exactly match what is generated by the old C++ wrapper.

[dellaert]

Since 4.0.3 is out, we now need testers for the new MATLAB wrapper, since the generated code currently does not exactly match what is generated by the old C++ wrapper.

It would be nice if this call came with instructions and a concrete ask :-) When fixed, also announce on internal slack?

[ProfFan]

@dellaert Sure.

[varunagrawal]

@ProfFan I checked the issue with This declarations and it seems to work fine. I believe we can close this issue. 🙂

[varunagrawal]

Nvm I encountered it again. I can fix it after I get the CI up and running again.

[varunagrawal]

The This issue only happens when the class isn't templated, so that helps a lot.

[varunagrawal]

Also, FYI I fixed all the Matlab tests so the tests now run and they pass.

[varunagrawal]

This issue has been resolved 🎉