Overview of Data Conversion Classes

Overview

The data conversion classes are

• MWArray

• MWIndexArray

• MWCellArray

• MWCharacterArray

• MWLogicalArray

• MWNumericArray

• MWStructArray

Note   For complete reference information about the MWArray class hierarchy, see the MWArray Class Library Reference (available online only).

MWArray and MWIndexArray are abstract classes. The other classes represent the standard MATLAB array types: cell, character, logical, numeric, and struct. Each class provides constructors and a set of properties and methods for creating and accessing the state of the underlying MATLAB array.

There are some data types (cell arrays, structure arrays, and arrays of complex numbers) commonly used in the MATLAB product that are not available as native .NET types. To represent these data types, you must create an instance of eitherMWCellArray, MWStructArray, or MWNumericArray.

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Returning Data from MATLAB to Managed Code

All data returned from a MATLAB function to a .NET method is represented as an instance of the appropriate MWArray subclass. For example, a MATLAB cell array is returned as an MWCellArray object.

Return data is not automatically converted to a native array. If you need to get the corresponding native array type, call the ToArray method, which converts a MATLAB array to the appropriate native data type, except for cell and struct arrays. See Deploying a Component Using the Magic Square Example.

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Example of MWNumericArray in a .NET Application

Here is a code fragment that shows how to convert a double value (5.0) to a MWNumericArray type:

MWNumericArray arraySize = 5.0;
magicSquare = magic.MakeSqr(arraySize);

After the double value is converted and assigned to the variable arraySize, you can use the arraySize argument with the MATLAB based method without further conversion. In this example, the MATLAB based method is magic.MakeSqr(arraySize).

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Interfaces Generated by the MATLAB Builder NE Product

For each MATLAB function that you specify as part of a .NET component, the builder generates an API based on the MATLAB function signature, as follows:

• A single output signature that assumes that only a single output is required and returns the result in a single MWArray rather than an array of MWArrays.

• A standard signature that specifies inputs of type MWArray and returns values as an array of MWArray.

• A feval signature that includes both input and output arguments in the argument list rather than returning outputs as a return value. Output arguments are specified first, followed by the input arguments.

Single Output API

Note   Typically you use the single output interface for MATLAB functions that return a single argument. You can also use the single output interface when you want to use the output of a function as the input to another function.

For each MATLAB function, the builder generates a wrapper class that has overloaded methods to implement the various forms of the generic MATLAB function call. The single output API for a MATLAB function returns a single MWArray value.

For example, the following table shows a generic function foo along with the single output API that the builder generates for its several forms.

function [Out1, Out2, ..., varargout] = 
  foo(In1, In2, ..., InN, varargin)

public MWArray foo() 

public MWArray foo(
MWArray In1, 
MWArray In2
...
MWArray inN) 

public MWArray foo(
MWArray In1, 
MWArray In2, 
     ..., 
MWArray inN
params MWArray[] varargin
)

In the example, the input arguments In1, In2, and inN are of type MWArray objects.

Similarly, in the case of optional arguments, the params arguments are of type MWArray. (The varargin argument is similar to the varargin function in MATLAB — it allows the user to pass a variable number of arguments.)

Note   When you call a class method in your .NET application, specify all required inputs first, followed by any optional arguments. Functions having a single integer input require an explicit cast to type MWNumericArray to distinguish the method signature from a standard interface signature that has no input arguments.

Standard API

Typically you use the standard interface for MATLAB functions that return multiple output values.

The standard calling interface returns an array of MWArray objects rather than a single array object.

The standard API for a generic function with none, one, more than one, or a variable number of arguments, is shown in the following table.

function [Out1, Out2, ..., varargout] = 
  foo(In1, In2, ..., InN, varargin)

public MWArray[] foo(
int numArgsOut
) 

public MWArray [] foo(
int numArgsOut, 
MWArray In1
) 

public MWArray[] foo(
int numArgsOut, 
MWArray In1,
MWArray In2, 
... 
MWArray InN
) 

public MWArray[] foo(
int numArgsOut,
 MWArray in1,
 MWArray in2,
 ..., 
MWArray InN,
params MWArray[] varargin
)

Details about the arguments for these samples of standard signatures are shown in the following table.

feval API

In addition to the methods in the single API and the standard API, in most cases, the builder produces an additional overloaded method. If the original MATLAB code contains no output arguments, then the builder will not generate the feval method interface.

For a function with the following structure,

function [Out1, Out2, ..., varargout] = 
  foo(In1, In2, ..., InN, varargin)

The builder generates the following API, known as the feval interface,

public void foo 
            (int numArgsOut,
             ref MWArray [] ArgsOut, 
             MWArray[] ArgsIn)

where the arguments are as follows:

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Data Conversion Rules

MWArray Class Specification

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