Programming and Graphics

308 Introduction to C++ Programming and Graphics

//--- Evaluate the square:

engEvalString(oliver, "mat2 = mat^2");

cout << BuFFer;

//--- Retrieve the square:

mxArray * x2 = engGetVariable(oliver, "mat2");

double * square = mxGetPr(x2);

cout << "C++ domain:" << endl;

cout << square[0] <<""<<square[2] << endl;

cout << square[1] <<""<<square[3] << endl;

//--- End the session:

engClose(oliver);

return 0;

}

The session produces the following output on the screen:

>>

determinant =

-5

>>

mat2 =

916

817

C++ domain:

916

817

The indented output originates from theMatlabdomain, and the non-indented
output originates from the C++ domain. It is important to observe that the
Matlabmatrixx2is retrieved as the C++ vectorsquarein acolumn-wise
fashion.

Eigenvalues and eigenvectors

A complex number is composed of a real and an imaginary part. The real
and imaginary parts of a scalar, vector, or matrix produced byMatlabare
placed in consecutive memory blocks.

The following code contained in the filemuse2.ccdefines a matrix in the
C++ domain, callsMatlabto compute the eigenvalues and eigenvectors, and
transfers the results back to the C++ domain: