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Using MatLab Add-in for MS Visual Studio 6

By , 4 Jul 2003
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Introduction

Following the line of the article posted by A.Riazi, Solving engineering problem using MATLAB C API, I will show in this small example how to use M Functions inside our VC++ 6 project.

The project calculates the convolution of two vectors, and shows the resulting vector in the MsChart control. The function that performs the convolution is written in MatLab and then through the MatLab Add-in converted to C code ready to be used inside our app.

Requirements

You need Visual Studio 6 and MatLab Release 12 installed with the MatLab C Library and Matlab Compiler.

Installing the MatLab Add-in

The add-in automates the integration of M-files into Visual C++ projects. The add-in for Visual Studio is automatically installed on your system when you run either mbuild -setup or mex -setup and select Microsoft Visual C/C++ version 6. In order to use the add-in you must follow these steps:

  • Start MatLab, in the prompt type mbuild -setup
  • Follow the menus and choose MS Visual C++6.0.
  • Type the following commands in the matlab prompt :

    cd (prefdir)
    mccsavepath

These commands save the MatLab path to a file called mccpath in your user preferences directory (prefdir), ussually inside your documents and settings file. The path is used by the add-in because it runs outside Matlab and there is no other way for it to determine your Matlab path. If you add new directories to your Matlab path you will have to rerun this command if you want the add-in to see them.

  • Configure the Matlab Add-in for Visual Studio 6 to work within MSVisual C++.
    • Open MSVisualC++.
    • Select Tools -> Customize from the MSVC menu.
    • Click on the Add-ins and Macro Files tab.
    • Check MATLAB for Visual Studio on the Add-ins and Macro Files list and click Close.

The floating MATLAB add-in for Visual Studio toolbar appears. The checkmark directs MSVC to automatically load the add-in when you start MSVC again.

Calculating the convolution in Matlab

We will write a simple function in MatLab that will perform the convolution of two vectors:

In1 and In2 and store the result in out.

We actually can use any matlab built-in function or toolbox function inside our function here we use only the function conv for simplicity.

function out=MyFunc(In1,In2)
%Returns the convolution of vector IN1 and IN2
out=conv(In1,In2);

Save the function with the name MyFunc.m

Writing the Application

Use the MFC AppWizard (exe) option to generate a Dialog Based Application and call it conv. Create a Button which will calculate the convolution of two given vectors.

Add the code below to the button's Message Handler.

//x1 and x2 are the input array to do the computation
//res will have the result, we already know that the length 
//of the convolution of 2 vectors is (length(x1)+length(x2)-1)=19
double x1[]={1,2,3,4,5,6,7,8,9,0};
double x2[]={4,5,6,7,4,5,8,9,0,7};
double res[19];

//create the arrays that will be passed to MyFunc
mxArray* In1;
mxArray* In2;
mxArray* Out;

//we make them Real and have 10 values
In1=mxCreateDoubleMatrix(1,10,mxREAL);
In2=mxCreateDoubleMatrix(1,10,mxREAL);

//this make In1=x1;In2=x2
memcpy(mxGetPr(In1),x1,10*sizeof(double));
memcpy(mxGetPr(In2),x2,10*sizeof(double));

//Call to MyFunc.m that return the convolution of In1 and In2
Out=mlfMyFunc(In1,In2);

//now we have the result(Out) in a double array 'res'
memcpy(res,mxGetPr(Out),19*sizeof(double));

//Destroy matrices
mxDestroyArray(Out);
mxDestroyArray(In1);
mxDestroyArray(In2);

Copy MyFunc.m into your VC++ project directory. Now go to the MatLab Add-in and click the .m++ (Add m-files to current project) button:

Sample screenshot

Select Windows Console Exe from the Combo Box and check Generate main file and debug mode. Press OK.

Then select the MyFunc.m file and click Open. After a while you will see new files added to your project.

Sample screenshot

Under MATLAB M-files you will see our MyFunc.m, you can even edit it from inside Visual C++. Under MATLAB C/C++ are MyFunc.c and MyFunc_main.c, generated by the MatLab Compiler. And all the headers needed by the compiler.

We can't build the app yet, we must add the following lines to convDlg.cpp:

#include "matlab.h"
#include "MyFunc.h"

Now the project should be built without any problem.   

Points of Interest

The steps described here don't include the MSChart part, you can see it from the source code, but you can see that the calculation is done by placing a  breakpoint inside the button message handler and checking the value of the res vector after the line:

memcpy(res,mxGetPr(Out),19*sizeof(double));
<!------------------------------- That's it! --------------------------->

Well I hope this simple article be interesting for MatLab lovers, this is the first article I wrote, so I apologize if it is not clear enough. I will be glad to explain anything if you ask me. Greetings.

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

About the Author

Cambalindo
Software Developer Motorola
United States United States
Daniel Cespedes is now working on his final project to get the Electrical Engineering degree at the National University of Technology in Cordoba Argentina. He is developing a Computerized system for the study of Human Echolocation, the ability to detect obstacles with the echoes of self generated sounds.(yes like bats!!) at the CINTRA (Centro de Investigación y Transferencia Acústica).He uses MsVisual C++ 6 as a developing tool. He also work at the Software Research Lab at the University.
He comes from Sta.Cruz de la Sierra-Bolivia a paradise in SouthAmerica´s heart, where you can find pure air, nature contact, happy people, beautiful women etc.

Comments and Discussions

 
AnswerANSWER TO SOME OF YOUR PROBLEMS Pinmemberleevonk13-May-08 9:46 
GeneralRe: ANSWER TO SOME OF YOUR PROBLEMS Pinmemberleevonk13-May-08 10:08 
AnswerRe: ANSWER TO SOME OF YOUR PROBLEMS Pinmemberleevonk13-May-08 11:01 
here's how I finally got everything to work. read my advice in the two comments above (check capitalization of myfunc, include bin directories in the widnows PATH, etc.
 

%+++++++++++++++++++++++++++++++++++
%+++++++++--MATLAB M FILE--+++++++++
%+++++++++++++++++++++++++++++++++++
function out=MyFunc(a,b)
if ( a >= b)
out = a;
else
out = b;
end
%+++++++++++++++++++++++++++++++++++
 

 
//###################################
//#########--VC++ Code Below--#######
//###################################
 
//#######library modules linked to project:#########
// libmwlapack.lib libmex.lib libmx.lib
 
//include section
#include "stdafx.h"
#include "MatlabIntegrationTest.h"
#include "MatlabIntegrationTestDlg.h"
#include "matlab.h"
#include "myfunc.h"
#include "mat.h"
#include "conio.h"
#include
 

/*
this part below is in the OK buttons function
I modified the code posted in the instructions to be simpler
my code sends two numbers, x1 and x2 to the m-file, the m-file
decides which number is larger and sends it back to the c++ code
---
you can see the unmodified original code in the comments above each
line of my modified code
---
In order to see that the code was working correctly, I made an 'edit box'
in my GUI dialog, the variable associated with the edit box is m_Output
So at the end of my code I write the value returned to the c++ code from the
m-file to the edit box so you can see it. In the case of the two numbers I'm
sending the m-file in my code (4 and 6), it should show a 6 when you click the
GUI's ok button to run the program.
*/
 
void CMatlabIntegrationTestDlg::OnOK()
{
//double x1[]={1,2,3,4,5,6,7,8,9,0};
//double x2[]={4,5,6,7,4,5,8,9,0,7};
double x1[]={6};
double x2[]={4};
//double res[19];
double res[1];
 
//create the arrays that will be passed to MyFunc
 
mxArray* In1;
mxArray* In2;
mxArray* Out;
 
//we make them Real and have 10 values
//In1=mxCreateDoubleMatrix(1,10,mxREAL);
//In2=mxCreateDoubleMatrix(1,10,mxREAL);
In1=mxCreateDoubleMatrix(1,1,mxREAL);
In2=mxCreateDoubleMatrix(1,1,mxREAL);
 
//this make In1=x1;In2=x2
//memcpy(mxGetPr(In1),x1,10*sizeof(double));
//memcpy(mxGetPr(In2),x2,10*sizeof(double));
memcpy(mxGetPr(In1),x1,1*sizeof(double));
memcpy(mxGetPr(In2),x2,1*sizeof(double));
 
//Call to MyFunc.m that return the convolution of In1 and In2
 
Out=mlfMyfunc(In1,In2);
 
//now we have the result(Out) in a double array 'res'
//memcpy(res,mxGetPr(Out),19*sizeof(double));
memcpy(res,mxGetPr(Out),1*sizeof(double));
 
//send the returned value to an edit box of the GUI
double LeeOut;
LeeOut = res[0];
m_Output = LeeOut;
UpdateData(FALSE);
 
//extra debug message
MessageBox("hi");
 
//Destroy matrices
mxDestroyArray(Out);
mxDestroyArray(In1);
mxDestroyArray(In2);
 
}

GeneralRe: ANSWER TO SOME OF YOUR PROBLEMS PinmemberCambalindo14-May-08 3:14 

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