Integrate Function with Variable Number of Arguments

This example shows you how to create a .NET application using a MATLAB^® function that takes a variable number of arguments instead of just one.

In this example, you perform the following steps:

• Use the MATLAB Compiler SDK™ product to convert the MATLAB function drawgraph to a method of a .NET class (Plotter) and wrap the class in a .NET assembly (VarArgComp). The drawgraph function displays a plot of the input parameters and is called as a method of the Plotter class.

• Access the component in a C# application (VarArgApp.cs) or a Visual Basic^® application (VarArgApp.vb) by instantiating the Plotter class and using MWArray to represent data.

• Build and run the VarArgDemoApp application using the Visual Studio^® .NET development environment.

Files

MATLAB Functions	drawgraph.m extractcoords.m
MATLAB Function Location	matlabroot\toolbox\dotnetbuilder\Examples\VSVersion\NET\VarArgExample\VarArgComp\
C# Code Location	matlabroot\toolbox\dotnetbuilder\Examples\VSVersion\NET\VarArgExample\VarArgCSApp\VarArgApp.cs
Visual Basic Code Location	matlabroot\toolbox\dotnetbuilder\Examples\VSVersion\NET\VarArgExample\VarArgVBApp\VarArgApp.vb

Procedure

1. Copy the following folder that ships with the MATLAB product to your work folder:

   matlabroot\toolbox\dotnetbuilder\Examples\VSVersion\NET\VarArgExample
   

   At the MATLAB command prompt, navigate to the new VarArgExample\VarArgComp subfolder in your work folder.

2. Examine the drawgraph and extractcoords functions.

   function [xyCoords] = DrawGraph(colorSpec, varargin)
   
       numVarArgIn= length(varargin);
       xyCoords= zeros(numVarArgIn, 2);
   
       for idx = 1:numVarArgIn
           xCoord = varargin{idx}(1);
           yCoord = varargin{idx}(2);
           
           x(idx) = xCoord;
           y(idx) = yCoord;
           
           xyCoords(idx,1) = xCoord;
           xyCoords(idx,2) = yCoord;
       end
       
       xmin = min(0, min(x));
       ymin = min(0, min(y));
   
       axis([xmin fix(max(x))+3 ymin fix(max(y))+3])
       
       plot(x, y, 'color', colorSpec);
   
    
   

   function [varargout] = ExtractCoords(coords)
   
       for idx = 1:nargout
           varargout{idx}= coords(idx,:);
       end
   

3. Build the .NET component with the .NET Assembly Compiler app or compiler.build.dotNETAssembly using the following information:

   Field	Value
   Library Name	VarArgComp
   Class Name	Plotter
   Files to Compile	extractcoords.m   drawgraph.m

   For example, if you are using compiler.build.dotNETAssembly, type:

   buildResults = compiler.build.dotNETAssembly(["extractcoords.m","drawgraph.m"], ...
   'AssemblyName','VarArgComp', ...
   'ClassName','Plotter');

   For more details, see the instructions in Generate .NET Assembly and Build .NET Application.

4. Decide whether you are using C# or Visual Basic to access the component.

   • C#

     If you are using C#, write source code for a C# application that accesses the component.

     The sample application for this example is in VarArgExample\VarArgCSApp\VarArgApp.cs.

      VarArgApp.cs

     using System;
     
     using MathWorks.MATLAB.NET.Utility;
     using MathWorks.MATLAB.NET.Arrays;
     
     using VarArgComp;
     
     
     namespace MathWorks.Examples.VarArgApp
      {
       /// <summary>
       /// This application demonstrates how to call components 
       ///  having methods with varargin/vargout arguments.
       /// </summary>
       class VarArgApp
         {
           #region MAIN
     
           /// <summary>
           /// The main entry point for the application.
           /// </summary>
           [STAThread]
           static void Main(string[] args)
             {
               // Initialize the input data
               MWNumericArray colorSpec= new double[]
                                             {0.9, 0.0, 0.0};
               MWNumericArray data= 
                       new MWNumericArray(new int[,]{{1,2},{2,4},
                                            {3,6},{4,8},{5,10}});  
               MWArray[] coords= null;
     
               try
                 {
                   // Create a new plotter object
                   Plotter plotter= new Plotter();
     
                   //Extract a variable number of two element x and y coordinate 
                   //  vectors from the data array
                   coords= plotter.extractcoords(5, data);
     
                   // Draw a graph using the specified color to connect the 
                   //   variable number of input coordinates.
                   // Return a two column data array containing the input coordinates.
                   data= (MWNumericArray)plotter.drawgraph(colorSpec, 
                     coords[0], coords[1], coords[2],coords[3], coords[4]);
     
                   Console.WriteLine("result=\n{0}", data);
     
                   Console.ReadLine();  // Wait for user to exit application
     
                   // Note: You can also pass in the coordinate array directly.
                   data= (MWNumericArray)plotter.drawgraph(colorSpec, coords);
     
                   Console.WriteLine("result=\n{0}", data); 
      
                   Console.ReadLine();  // Wait for user to exit application
                 }
     
               catch(Exception exception)
                 {
                   Console.WriteLine("Error: {0}", exception);
                 }
             }
     
           #endregion
         }
       }
     

     The following statements are alternative ways to call the drawgraph method:

     data= (MWNumericArray)plotter.drawgraph(colorSpec, 
                     coords[0], coords[1], coords[2],coords[3], coords[4]);
     ...
     data= (MWNumericArray)plotter.drawgraph((MWArray)colorSpec, coords);
     

   • Visual Basic

     If you are using Visual Basic, write source code for a Visual Basic application that accesses the component.

     The sample application for this example is in VarArgExample\VarArgVBApp\VarArgApp.vb.

      VarArgApp.vb

     Imports System
     
     Imports MathWorks.MATLAB.NET.Utility
     Imports MathWorks.MATLAB.NET.Arrays
     
     Imports VarArgComp
     
     
     Namespace MathWorks.Demo.VarArgDemoApp
     
     
     ' <summary>
     ' This application demonstrates how to call components having methods with 
     '   varargin/vargout arguments.
     ' </summary>
     Class VarArgDemoApp
         
     #Region " MAIN "
     
             ' <summary>
             ' The main entry point for the application.
             ' </summary>
             Shared Sub Main(ByVal args() As String)
     
                 ' Initialize the input data
                 Dim colorSpec As MWNumericArray = 
                   New MWNumericArray(New Double() {0.9, 0.0, 0.0})
                 Dim data As MWNumericArray = 
                   New MWNumericArray(New Integer(,) {{1, 2}, {2, 4}, {3, 6}, {4, 8}, {5, 10}})
                 Dim coords() As MWArray = Nothing
     
                 Try
     
                     ' Create a new plotter object
                     Dim plotter As Plotter = New Plotter
     
                     'Extract a variable number of two element x and y coordinate 
                     ' vectors from the data array
                     coords = plotter.extractcoords(5, data)
     
                     ' Draw a graph using the specified color to connect the variable number of 
                     '  input coordinates.
                     ' Return a two column data array containing the input coordinates.
                     data = CType(plotter.drawgraph(colorSpec, coords(0), coords(1), coords(2), 
                        coords(3), coords(4)), _
                                  MWNumericArray)
     
                     Console.WriteLine("result={0}{1}", Chr(10), data)
     
                     Console.ReadLine()  ' Wait for user to exit application
     
                     ' Note: You can also pass in the coordinate array directly.
                     data = CType(plotter.drawgraph(colorSpec, coords), MWNumericArray)
     
                     Console.WriteLine("result=\{0}{1}", Chr(10), data)
     
                     Console.ReadLine()  ' Wait for user to exit application
     
     
                 Catch exception As Exception
                     Console.WriteLine("Error: {0}", exception)
                 End Try
             End Sub
     #End Region
     
         End Class
     End Namespace
     

     The following statements are alternative ways to call the drawgraph method:

     data = CType(plotter.drawgraph(colorSpec, coords(0), coords(1), coords(2), 
            coords(3), coords(4)), MWNumericArray)
     ...
     data = CType(plotter.drawgraph(colorSpec, coords), MWNumericArray)

   In either case, the VarArgApp program does the following:

   • Initializes three arrays (colorSpec, data, and coords) using the MWArray class library

   • Creates a Plotter object

   • Calls the extracoords and drawgraph methods

   • Uses MWNumericArray to represent the data needed by the methods

   • Uses a try-catch block to catch and handle any exceptions

5. Open the .NET project file that corresponds to your application language using Visual Studio.

   • C#

     If you are using C#, the VarArgCSApp folder contains a Visual Studio .NET project file for this example. Open the project in Visual Studio .NET by double-clicking VarArgCSApp.csproj in Windows^® Explorer. You can also open it from the desktop by right-clicking VarArgCSApp.csproj and selecting Open Outside MATLAB.

   • Visual Basic

     If you are using Visual Basic, the VarArgVBApp folder contains a Visual Studio .NET project file for this example. Open the project in Visual Studio .NET by double-clicking VarArgVBApp.vbproj in Windows Explorer. You can also open it from the desktop by right-clicking VarArgVBApp.vbproj and selecting Open Outside MATLAB.

6. Create a reference to your assembly file VarArgComp.dll located in the folder where you generated or installed the assembly.

7. Create a reference to the MWArray API.

   If MATLAB is installed on your system	matlabroot\toolbox\dotnetbuilder\bin\win64\<framework_version>\MWArray.dll
   If MATLAB Runtime is installed on your system	<MATLAB_RUNTIME_INSTALL_DIR>\toolbox\dotnetbuilder\bin\win64\<framework_version>\MWArray.dll

8. Build and run the VarArgApp application in Visual Studio .NET.

   The program displays the following output:

   result=
        1     2
        2     4
        3     6
        4     8
        5    10