CODEWITHSUNDEEP
c#.netmatlab.net-assemblymatlab-compiler
Randhir Rawatlal
Randhir Rawatlal

Reputation: 363

Integrating matlab functions into c# project

I have a nice .net assembly of core matlab functions, created of course with the matlab compiler. For functions that accept numbers or arrays of numbers, this is fine; I can write code in c# without having to revert to matlab (well, the RCM has to be installed; that’s fine).

For functions that must reference other functions, however, the only way I can find so far to get a c# programme going is to compile both functions into the assembly. To explain better, let’s say I have a library in which I’ve stored the ode45 routine. If I want to solve a specific equation, let’s say something simple like dy/dx = -y, then I have to create a matlab script file which may be written as follows:

function dydx = diffeq(x, y)
dydx = -y

[obviously the analytical solution exists, but for the sake of this example let’s say I want to solve it this way]

Now in order to solve this equation, I would have to add this function as a method in my class to be compiled into the .net assembly. This of course ruins the generality of my library; I want application-specific equations in a different library to my core math function library. That is, the ODE45 method should reside in a “more core” library than the library in which the “diffeq” method would reside.

More than that, I would much prefer to create the “diffeq” method in a c# class that I can edit directly in e.g. VS2012. I would like to edit the equation directly rather than having to enter matlab each time and recompile an assembly.

To solve this problem, I have gone to the extent of decompiling the assembly which contains both the ode45 code and my differential equation method; it turns out the assembly is nothing but an interface to the MCR; the diffeq methods in the assembly return something like the following:

return mcr.EvaluateFunction(numArgsOut, “diffeq”, new object[0]);

We note that the function/method “diffeq” is not part of the MCR; MCR does not change. However, I can’t find the equation anywhere in the assembly.

Which begs the question “Dude, where’s my function?”

There is a ‘resources’ component of the assembly in which we find [classname].ctf, and in that we’ll find some machine code. This looks encrypted, but the equation might be hidden in there. If so, that would be a deliberate attempt to prevent when I am attempting, and kudos to MathWorks for making it impossible for me to avoid having to enter the matlab application!

However, there doesn’t seem to be anything in licensing to prevent what I want to do; I think it would be great if mathworks would allow as open an approach as that, but in the interrim, does anyone know how to do this?

Upvotes: 3

Views: 1867

Answers (1)

Amro
Amro

Reputation: 124563

The "MATLAB Compiler" has a somewhat misleading name. It is more of a deployment solution than a compiler in the actual sense (see note below). It is mainly intended to distribute MATLAB applications to end-users without requiring a full MATLAB installation on their part (only the royalty-free MCR runtime needs to be installed).

The MCR is in fact a stripped-down version of the MATLAB engine along with accompanying libraries.

When you use MATLAB Compiler to generate a binary package, the result is a target-specific wrapper (be it a standalone application, C/C++ shared library, Java package, or a .NET assembly) that calls the MCR runtime. The binary generated includes an embedded CTF archive containing all the original MATLAB content (your M-files and other dependencies) but in an encrypted form. When first executed, the CTF archive is extracted to a temp folder, and the M-files (still encrypted) are then interpreted by the MCR at runtime like typical MATLAB code.

There is an option in deploytool (mcc -C) to tell the compiler not to embed the CTF archive inside the binary as a resource, instead to place it as a seperate file next to the generated binary (this CTF archive can be inspected as a regular ZIP-file, but the source files inside are still encrypted of course).

See the following documentation page for more information:

Application Deployment Products and the Compiler Apps

PS: The truth is MATLAB Compiler started out as a product to convert MATLAB code into full C/C++ code which used the now discontinued "MATLAB C/C++ Math Library" (no runtime requirement, you just compile the generated C++ code and link to certain shared libraries; the result is a true compiled executable not a wrapper). This functionality completely changed around the time MATLAB 7 was released (the reason being that the old way only supported a subset of the MATLAB language, while using the current MCR mechanism enables deploying almost any code). Years later, MATLAB added a new product to replace the once-removed functionality of code translation, namely the MATLAB Coder.

Upvotes: 1

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