Using mexCallMATLAB to instantiate an object ?

Hello,

I'm trying to embed matlab into my C++ code, using the Engine API. I want to instantiate an object of a specific class ("Vector", say), and then inject that into the workspace via engPutVariable.

To instantiate the Vector, I'm trying to use

mxArray *rhs = ...; // argument
mxArray *lhs = 0;
mexCallMATLAB(1, &lhs, 1, &rhs, "Vector");

However, I'm observing a segmentation fault at the mexCallMATLAB call. Does anyone see what I'm doing wrong here ? Is there a better way to construct an instance of a specific Matlab class from C++ ?

Many thanks, Stefan

Answer 1

[James Tursa]

You can't use any of the mex___ API functions with the MATLAB Engine, you have to use the eng___ API functions. Since there is no engCallMATLAB function in the API, you can use this substitute instead from the FEX:

http://www.mathworks.com/matlabcentral/fileexchange/17494-engcallmatlab

[James Tursa]

P.S. I hope your object isn't huge because putting and getting variables from the Engine requires a deep copy, and the API gives you *no* direct pointer access to your object properties (don't ask me why).

[James Tursa]

I will qualify my previous statement by stating that it *is* possible to have a mex function that opens and calls an Engine. In that case one can use unofficial methods to get pointers to the object properties, but it still does not avoid the deep copy necessary between the mex routine and the Engine.

Answer 2

[Kaustubha Govind]

Have you tried following the documentation examples? As far as I know, the Engine API requires you to use engEvalString to call into functions. mexCallMATLAB is used only in MEX-functions.