Tutorial: How to use a compiled Matlab function in C#

In this small tutorial I will explain you:

• How to compile a Matlab function into a DLL
• Use the generated Matlab dll into a small C#-console program

Requirements:

• VisualStudio 2015 or greater
• Matlab 2018b 

Creating the .Net Matlab DLL

Create a matlab-file: MatlabThreeFunc.m

With the following content:

function [x2, sinx, expx]=MatlabThreeFunc(xIn)

% [x2, sinx, expx]=MatlabThreeFunc(xIn)

% Matlab test function

    x2=xIn.*xIn;

    sinx = sin(xIn);

    expx = exp(xIn);

end

As you see this simple function calculate the squared-, sin- and the exp- values of the input array xIn.

Navigate to the folder containing the file/function just created and execute the fololwing command:

mcc -W 'dotnet:MyMatlab.V2018b,WrapperClass,4.5,Private,local'  -T link:lib   ./MatlabThreeFunc.m;

This  will create a .Net dll, named V2018b.dll (version 4.5 of the Framework), containing a Class named WrapperClass and located in the namespace: MyMatlab.V2018b

In my My personal convention is to use part of the namespace (V2018b) to indicate which Matlab version I used to generate the dll. This is important when distributing your application. 

In my case, I want to run the application on other Computer I need to install the required Matlab Runtime 9.5 (=> https://www.mathworks.com/products/compiler/matlab-runtime.html)

Using the DLL in a C# project

Create a new Console Application:

Before you add a reference to the Just created DLL (=> V2018b.dll) it is important that you remove the VisualStudio default setting Prefer 32 Bit, otherwise you'll get a Runtime Type Exception from the Matlab dll. (=> Since Version 2015b, Matlab is ONLY 64 bit!)

Remove"Prefer 32Bit" 

Add the TWO Matlab-References to your project:

• V2018b.dll 
• MWArray.dll (this is located under :  C:\Program Files\MATLAB\R2018b\toolbox\dotnetbuilder\bin\win64\v4.0\MWArray.dll)

And now the code:

CODE:

using System;

using MathWorks.MATLAB.NET.Arrays;

namespace MatlabFuncInCSharp

{

    class Program

    {

        static void Main(string[] args)

        {

            Console.WriteLine("Running...");

            // a basic double-array for the tests

            double[] dArrayInput = new double[5] { 0.1, 0.2, 0.3, 0.4, 0.5 };

            // convert the C#-array into the equivalent MatLab class

            MWNumericArray matArrayInput = new MWNumericArray(dArrayInput);

            Console.WriteLine("Instantiating WrapperClass...");

            MyMatlab.V2018b.WrapperClass oWrapperClass = new MyMatlab.V2018b.WrapperClass();

           

            int iExpectedNumberOfOutputs = 3;  // we want ALL 3 outputs of "MatlabThreeFunc"

            Console.WriteLine("Callinng MatlabThreeFunc...");

            MWArray[] matOutput = oWrapperClass.MatlabThreeFunc(iExpectedNumberOfOutputs, matArrayInput);

            

            // matOutput contains 3 elements

            MWNumericArray matX2Array = (MWNumericArray)matOutput[0]; // casting required!

            MWNumericArray matSinXArray = (MWNumericArray)matOutput[1]; // casting required!

            MWNumericArray matExpXrray = (MWNumericArray)matOutput[2]; // casting required!

            Console.WriteLine("Converting output into C#-Arrays...");

            // back to the C#-world...

            double[] dX2array = (double[])matX2Array.ToVector(MWArrayComponent.Real);

            double[] dSinXarray = (double[])matSinXArray.ToVector(MWArrayComponent.Real);

            double[] dExpXarray = (double[])matExpXrray.ToVector(MWArrayComponent.Real);

            Console.WriteLine("Press any key to exit!");

            Console.ReadKey();

        }

    }

}

I hope you found this post useful. A small video would have been wayyyyyyyyyyy better but I don't have the time for it. 

References:

• Mathworks: https://www.mathworks.com/help/compiler_sdk/ml_code/mcc.html#butg_5w
• Mathworks' samples: C:\Program Files\MATLAB\R2018b\toolbox\dotnetbuilder\Examples\VS15\NET