Class properties allow an object to retain an internal state between method calls.
Global variables are variables that are
declared in the MATLAB® product with the global keyword. MATLAB Compiler SDK™ automatically
converts all global variables shared by the MATLAB files that
make up a class to properties on that class.
Properties are useful when you have a large array containing values that do not change often, but are operated on frequently. In such cases, setting the array as a property saves the overhead required to pass it to a method every time it is called.
The following example shows how to use a class property in a matrix factorization class. The example develops a class that performs Cholesky, LU, and QR factorizations on the same matrix. It stores the input matrix as a class property so that it is not passed to the factorization routines.
Consider these three MATLAB files.
Cholesky.m
function [L] = Cholesky()
global A;
if (isempty(A))
L = [];
return;
end
L = chol(A);
LUDecomp.m
function [L,U] = LUDecomp()
global A;
if (isempty(A))
L = [];
U = [];
return;
end
[L,U] = lu(A);
QRDecomp.m
function [Q,R] = QRDecomp()
global A;
if (isempty(A))
Q = [];
R = [];
return;
end
[Q,R] = qr(A);
These three files share a common global variable A.
Each function performs a matrix factorization on A and
returns the results.
To build the class:
Create a compiler project named mymatrix with
a version of 1.0.
Add a single class called myfactor to
the component.
Add the above three MATLAB files to the class.
Build the component.
Use the following Visual Basic® subroutine to test the myfactor class:
Sub TestFactor()
Dim x(1 To 2, 1 To 2) As Double
Dim C As Variant, L As Variant, U As Variant, _
Q As Variant, R As Variant
Dim factor As myfactor
On Error GoTo Handle_Error
Set factor = New myfactor
x(1, 1) = 2#
x(1, 2) = -1#
x(2, 1) = -1#
x(2, 2) = 2#
factor.A = x
Call factor.cholesky(1, C)
Call factor.ludecomp(2, L, U)
Call factor.qrdecomp(2, Q, R)
Exit Sub
Handle_Error:
MsgBox (Err.Description)
End Sub
Run the subroutine, which does the following:
Creates an instance of the myfactor class
Assigns a double matrix to the property A
Calls the three factorization methods