Variable Number of Arguments

Note

This example is similar to Integrating a Simple MATLAB Function, except that the MATLAB^® function to be encapsulated takes a variable number of arguments instead of just one.

The purpose of the example is to show you the following:

How to use the MATLAB Compiler SDK™ product to convert a MATLAB function, drawgraph, which takes a variable number of arguments, to a method of a .NET class (Plotter) and wrap the class in a .NET assembly (VarArgComp). The drawgraph function (which can be called as a method of the Plotter class) displays a plot of the input parameters.
How to access the component in a C# application (VarArgApp.cs) by instantiating the Plotter class and using MWArray to represent data.
Note
For information about these data conversion classes, see the MATLAB MWArray Class Library Reference, available in the matlabroot\help\dotnetbuilder\MWArrayAPI folder, where matlabroot represents your MATLAB installation folder
How to build and run the VarArgDemoApp application, using the Visual Studio^® .NET development environment.

Step-by-Step Procedure

If you have not already done so, copy the files for this example as follows:
1. Copy the following folder that ships with the MATLAB product to your work folder:
```
matlabroot\toolbox\dotnetbuilder\Examples\VSVersion\NET\VarArgExample
```
2. At the MATLAB command prompt, cd to the new VarArgExample subfolder in your work folder.

Write the MATLAB functions as you would any MATLAB function.

The code for the functions in this example is as follows:

drawgraph.m

extractcoords.m

This code is already in your work folder in \VarArgExample\VarArgComp\.

From the MATLAB apps gallery, open the Library Compiler app.
Build the .NET component. See the instructions in Generate a .NET Assembly and Build a .NET Application for more details. Use the following information:

Project Name VarArgComp
Class Name Plotter
File to compile extractcoords.m drawgraph.m

Write source code for an application that accesses the component.

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

The program listing is shown here.

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 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

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);

Build the VarArgApp application using Visual Studio .NET.
1. 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 > Open Outside MATLAB.
2. Add a reference to the MWArray component, which is matlabroot\toolbox\dotnetbuilder\bin\architecture\framework_version\mwarray.dll.
3. Add or, if necessary, fix the location of a reference to the VarArgComp component which you built in a previous step. (The component, VarArgComp.dll, is in the \VarArgExample\VarArgComp\x86\v4.0\debug\distrib subfolder of your work area.)
Build and run the application in Visual Studio .NET.

Documentation