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Posted 18 Nov 2003


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1..2..3 ways of integrating MATLAB with the .NET

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18 Nov 20037 min read
A library to access MATLAB from .NET and a comparision of three possible methods to implement it.


In this article, I want to describe three possible techniques of integration of the .NET Framework with MATLAB, then I'll chose one of them and create a library for accessing MATLAB functionalities. The final objective is to create a C# component that encapsulates an M-file, much like MATLAB R13 COM Builder does. The only requirement of this project is to have MATLAB installed.


MATLAB is a powerful scientific tool for math manipulation, specifically matrix manipulations, with its own scripting language, where files are .M files. Usually it's used as a standalone program, but can be integrated in two ways using other languages like Java, C and FORTRAN. With the first usage, we declare a new function or component in a native language that extends the functionalities of MATLAB, usually to improve the execution speed; this approach uses the MEX system. The second usage, described in this article, uses MATLAB functionalities from an external program, this time a program in the .NET framework. In this schema, the Java language has a special role because, from the R12 (a.k.a. 6.0), MATLAB is Java-based (specifically for the multiplatform GUI functionalities) and you can easily use Java classes in both ways. To use MATLAB from an external program, there are three possible solutions:

  1. low level C API
  2. DDE
  3. COM

I'll describe these solutions, implement in C#, from the easiest and highest level to the most difficult and efficient. Then I'll use the C API interface, to create first a wrapping class that calls the C APIs. Finally I'll show a tool to generate a C# class that encapsulates easily, a MATLAB algorithm, stored in a m-file, and publish the functionality as an object oriented set of methods. For example, given the following m-file that uses the built-in function magic:

function y = mymagic(x)
    y = magic(x);

the idea is to create a .NET library that gives the possibility to write a component like:

class MyMagic { 
   public static Matrix mymagic(Matrix m);

Possible MATLAB - .NET bindings

Solution 1 - COM approach

MATLAB exposes itself as a COM Automation Server, so we can use the .NET COM Interoperability to use its functions: we can work directly using a Type Library or using only the Dispatch interface. The progid of the server is Matlab.Application.

This code creates the server and executes a command cmd:

m = CreateObject("Matlab.Application")

All the data transfer from MATLAB and our program is done through COM data types, and matrices are represented as SAFEARRAY(double) pointers, talking in COM terms. Using the COM interoperability, we can use double arrays.

double [,] MReal;
double [] MImag;
Result = Matlab.Execute("a = [ 1 2 3 ; 4 5 6 ; 7 8 9];");
call m.GetFullMatrix("a", "base", MReal, MImag);
call m.PutFullMatrix("b", "....)

The second parameter base is the workspace where to find the matrix variable a. According to the documentation, we have two main workspaces: base and global.

This solution is quite slow because of the COM type exchange, so it's better that we go ahead finding another way. Anyway, it is present in the article source code under the folder COMMATLib that exposes a Matrix class.

Solution 2 - DDE

The Dynamic Data Exchange is a quite old but powerful service of Windows that lets applications communicate and exchange data. It's the ancestor of the whole COM and so it's the grandfather of the whole .NET. Again, as with the COM solution, we have a client, our .NET program, and the server, the MATLAB DDE Server, that communicates.

A DDE communication is made with a Service Name, like Matlab or WinWord, about a topic of discussion, like System or Engine, and is based on the exchange of data elements called items.

The problem with the DDE exchange is the data types used to exchange information, because it uses the Windows clipboard data types. Specifically MATLAB supports:

  • Text for operation results, and matrix data exchange (gulp!);
  • Metafilepict for image transfer;
  • XLTable for MATLAB-Excel data exchange;

This time we create a DDE communication with MATLAB and evaluates expressions using the EngEvalString item; to get or set Matrix data, we use an item with the same name of the matrix.

I've created a wrapper class called DDEMatlab with the same interface as COMMatlab, but this time we can exchange pictures to, like the one returned by the plot command. Anyway, the very problem with DDE is the matrix data exchange that is all text based.

Solution 3 - C API

The direct access to the MATLAB C API is the best solution in terms of performance and features, just let use P/Invoke and some unsafe pointer operations.

The C library internally uses Unix pipes or the COM to communicate with the main MATLAB instance, but in this case the data transfer is done using blocks of raw memory instead of the SAFEARRAY. So we can use the unsafe capabilities of C# to transfer efficiently matrices from and to MATLAB, it's just necessary to remember that MATLAB stores data in column wise order.

The structure of this solution is described later, with some examples of usage.

Comparison of the solutions

I've tested the three solutions too see the performance differences between them, but it's easy to imagine the results ahead: the test was done writing and reading a matrix of 200 by 200 elements. The following table synthesizes the results:

SolutionMatrixFigures?Timing ReadTiming Write
DDE OptXLTableYes60ms80ms
Nativedouble*TODO 10ms20ms

The matnet library

The matnet library encapsulates the access to the MATLAB engine using the classic P/Invoke mechanism, exposed by the class MATInvoke, and provides the following features:

  • direct access to matrices, stored with different formats (Matrix class)
  • access to MAT files to load data stored in binary format (MATFile class)
  • evaluation of expressions (Evaluate method of the EngMATAccess class)

Examples and Usage

The basic usage of the matnet library requires to create an instance of the EngMATAccess that opens the communication with a MATLAB instance, or if not present, starts it up. Then the user can create instances of the Matrix class to store its data, and send evaluation commands to MATLAB.

using (EngMATAccess mat = new EngMATAccess())
    mat.Evaluate("A = [ 1 2 3; 3 5 6]"));
    double [,] mx = null;
    mat.GetMatrix("A", ref mx);

There are also two more interesting examples of usage.

Interaction with the Imaging Toolbox and Bitmaps

The mateng library gives also the possibility to interact with Bitmap as MATLAB matrices, and use the MATLAB Imaging Toolbox. The program ImageDemo in the demo source code loads an image and processes it using the imnoise function using MATLAB, in this case the problem is the startup time if there are no MATLAB instances running. Internally MATLAB stores images as byte type three dimensional matrices in column wise order, as shown in the following diagram. Maybe the integration with the Bitmap class could be put inside a matnet.imaging library.


Access with DLL

One of the interesting features of MATLAB is the translation of M-files into DLL libraries that can be used to distribute an algorithm in a very efficient form. The matnet library can be used to access also a custom DLL library (see example code). When an M-file is translated into a DLL, a function named AA is exposed as mlfAA, with Matrix parameters. These functions can be accessed from P/Invoke, for example an M-file with the function AA compiled as AAX.dll:

function x = AA(b)
    x = b + 2

Can be accessed with the class:

class MyDLL
    static extern IntPtr mlfAA(IntPtr a);

    static public Matrix mlfAA(Matrix m)
        return new Matrix(mlfAA((IntPtr)m));

Conclusions and Future Ideas

This article introduces the matnet .NET library as a method to access MATLAB functionalities from .NET applications in a very efficient way. This solution has been compared with the other two solutions (DDE & COM) available from MATLAB. The matnet library can be used to work directly with MATLAB or to expose M-files as components, it's also possible to interact with the imaging toolbox and bitmaps.

There are some things still missing:

  • a tool, M2NET, that encapsulates automatically an M-file as a .NET component or a user custom library
  • the extraction of figure and plots as Bitmap objects
  • make it work on Linux with Mono (sorry, but I haven't MATLAB for Linux)


This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

A list of licenses authors might use can be found here


About the Author

Emanuele Ruffaldi
Software Developer (Senior) Scuola Superiore S.Anna
Italy Italy
Assistant Professor in Applied Mechanics working in Virtual Reality, Robotics and having fun with Programming

Comments and Discussions

Questionthere is no matlab in my COM Pin
elibushehri30-Mar-15 2:17
Memberelibushehri30-Mar-15 2:17 
QuestionUnable to load DLL 'libeng.dll'. Pin
User 699122529-Jan-15 8:15
MemberUser 699122529-Jan-15 8:15 
Questionproblem with enrty point libmx.dll Pin
Member 1116651324-Oct-14 2:56
MemberMember 1116651324-Oct-14 2:56 
QuestionHow to deal with MATLAB return values Pin
mwpowellhtx5-Jun-14 11:14
Membermwpowellhtx5-Jun-14 11:14 
GeneralGood article especially COM bindings Pin
mwpowellhtx5-Jun-14 4:11
Membermwpowellhtx5-Jun-14 4:11 
Questionhow to read a signal from vb10 to matlab? Pin
Member 1006644420-May-13 20:46
MemberMember 1006644420-May-13 20:46 
QuestionTHNX Pin
Member 998837614-Apr-13 23:29
MemberMember 998837614-Apr-13 23:29 
QuestionFor simple numeric types with DllImport? Pin
rbaleksandar12-Dec-12 6:44
Memberrbaleksandar12-Dec-12 6:44 
Question5 Pin
cimadure11-Nov-12 10:34
Membercimadure11-Nov-12 10:34 
QuestionUsing matnet library with OCTAVE? Pin
Member 943088714-Sep-12 8:36
MemberMember 943088714-Sep-12 8:36 
GeneralMy vote of 5 Pin
Johannes Hillert14-Jun-12 8:41
MemberJohannes Hillert14-Jun-12 8:41 
GeneralMy vote of 5 Pin
Manoj Kumar Choubey13-Feb-12 1:02
professionalManoj Kumar Choubey13-Feb-12 1:02 
QuestionI guess the library doesn't work with MATLAB 7.12.0 (R2011a) Pin
Lannyland29-Nov-11 9:57
MemberLannyland29-Nov-11 9:57 
NewsRe: I guess the library doesn't work with MATLAB 7.12.0 (R2011a) Pin
Johannes Hillert15-Jun-12 10:11
MemberJohannes Hillert15-Jun-12 10:11 
QuestionHave problem when create neural network from c sharp! Pin
Member 801865928-Oct-11 19:17
MemberMember 801865928-Oct-11 19:17 
GeneralMy vote of 5 Pin
Sašo Mađarić3-May-11 9:55
MemberSašo Mađarić3-May-11 9:55 
GeneralMy vote of 1 Pin
abo_yehia30-Apr-11 19:23
Memberabo_yehia30-Apr-11 19:23 
Questionaccess violation issue Pin
kumar dhruva 26-Jan-11 12:00
Memberkumar dhruva 26-Jan-11 12:00 
GeneralDB Pin
devvvy30-Jul-10 0:57
Memberdevvvy30-Jul-10 0:57 
GeneralMatlab and Pin
hardikyjoshi10-Feb-10 0:02
Memberhardikyjoshi10-Feb-10 0:02 
GeneralMatlab .Net Builder Pin
coffeemist16-Nov-09 3:40
Membercoffeemist16-Nov-09 3:40 
GeneralRe: Matlab .Net Builder Pin
Roy65124-Jan-10 9:46
MemberRoy65124-Jan-10 9:46 
GeneralURGENT: two dimensional matrix of mixed type? {string, int, double, datetime} [modified] Pin
devvvy1-Aug-09 23:08
Memberdevvvy1-Aug-09 23:08 
GeneralIntegrating matlab and .net Pin
osgarcia29-Jul-09 3:15
Memberosgarcia29-Jul-09 3:15 
GeneralOne more way of integrating MATLAB with .NET Pin
vernicht25-Jul-09 14:35
Membervernicht25-Jul-09 14:35 

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