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

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.

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

Build the .NET component with the Library 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.

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

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

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

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

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`

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
```