C++ Source Code to MATLAB

Hey everyone,

Here's what I am trying to do. I have found some great source code online for a free simulation software written in C++. While the software is great, I'd like to integrate it into MATLAB. I understand that using MEX functionality in MATLAB you can use C++ source code in MATLAB. I'm not too familiar with this, so a tutorial or links to help me out would be great. I can provide a link to the source code if needed? But I'm really looking for a general implementation.

I read through some documentation but as one can expect the learning curve is significant.

[James Tursa]

Is this simulation interactive, or will it run essentially as a batch job once given some inputs? What is the output of the simulation? Some variables or plots or files or ...?

[Walter Roberson]

If you can create static class methods with extern "C" to interface to the simulation functions, then you can probably call the routines by using loadlibrary()

Note: loadlibrary() does not work to call general C++ methods, only things that extern "C"

[Hanif]

The output of the simulation generates binary files that need further analysis. The inputs into the simulation are saved as a binary function - the code searches for a specific filename or uses default simulation parameters.

Answer 1

[Jan]

Integrating some C++ code in a mex file is not hard: The mex file is started at the entry function "mexFunction". In tis function 3 things happen:

1. Input arguments comming from Matlab are converted to C++ variables,
2. The C++ functions are called,
3. The output is converted back to Matlab variables.

For the 1st job, e.g. mxGetPr() gets the pointer to the data of a Matlab double array. mxGetM /mxGetN gets the dimensions of matrices, etc. Check the types of the inputs by mxIsDouble and reject unexpected types, otherwise the C++ part will crash.

The 3rd job uses e.g. mxCreateDoubleMatrix(). This creates a matrix without setting the values. Either copy the results from the C++ part using memcpy, or create the output arrays initially and provide a pointer to the reserved memory directly to the C++ part.

You see, the mexFunction is the gateway between Matlab and C++ only.

[Hanif]

The MEX file seems to be the key to the solution. I read: https://www.mathworks.com/help/matlab/matlab_external/standalone-example.html

Please clarify the following:

- Lets say I have a C function that initiates my simulation, but calls other C files for different parts of the simulation. Do I need a MEX file for each of the different C files or just one for my main? In other words - Once the C code that initialises and starts the simulation is called, will it automatically call each C file and run or does each C file used for the simulation need to be included in a MEX file?

[James Tursa]

Include all of your source files in one mex command so they will all get linked together into one mex routine.

[Hanif]

Such as:

#include "File1.h"

#include "File2.h"

#include "File3.h"

etc..