Send variable from c to matlab

Hi all,

I have a c program that set variable into matlab, using matlab Engine.

ep = engOpen(NULL);
...
engPutVariable(ep, "var", var);

Everything is OK except that I want to send the variable,

to regular matlab workspace

and not to matlab Engine.

Any help ???

thx

[Marisol Sierra]

Hey did you solve this problem?

Answer 1

[Walter Roberson]

Your C program is the "MATLAB engine" in MATLAB terminology.

I have not been able to establish this as a fact so far, but as best I can tell reading between the lines, engPutVariable() writes the variable into the "base workspace" of the MATLAB process associated with the engine.

There is no mechanism provided to write a variable in to the workspace of a particular function because no functions can be running in the MATLAB process at the time engPutVariable() is executed (or so my reading suggests.)

[zohar]

Hi Walter,

What do you mean " There is no mechanism provided to write a variable in to the workspace of a particular function " ?

When I execute the command engOpen(NULL) it's open a weird matlab workspace , who looks like an old version of matlab and not the regular matlab workspace.

Any suggestion ?

[Walter Roberson]

What does a "regular matlab workspace" look like to you?

Regular MATLAB offers:

- A "base" workspace. This is the same workspace that you get if you work entirely at the command line. The variables that exist by default in the "base" workspace are only "i" and "j", both with the value sqrt(-1) . Everything else, including "ans", is only created at need.

- A "global" workspace. This workspace is accessible on a variable-by-variable basis, by using the "global" command followed by a variable name to indicate that the global instance should be accessed. There are no variables in the global workspace by default.

- one workspace per function which is currently in the call chain (either actively running, or called another function and so was suspended itself, or was interrupted by a timer or a callback). This workspace contains all of the variables used by the function, and other than in special circumstances, the workspace will have all those variables cleared out when the workspace goes out of scope. By default, each function executing or in temporary suspension has a separate workspace.

- one workspace per function that is not currently in the execution stack, if the function is the owner of a variable that is being used as part of an active closure. This one is a bit difficult to explain. By default, closures do not exist.

None of these different types of workspaces has any obviously different appearance than any other. You would probably have to go back to MATLAB version 4 for obvious differences in the look of a workspace.

Are you perhaps talking about a desktop or inspector tool of some kind? Or are you perhaps referring to the appearance of the command prompt or command line??

Perhaps posting a screen short might help.

[zohar]

Hi Walter and many thanks

OK, I understand what you are saying.

The solution :

There is workspace("weird matlab workspace") and desktop environment ("regular matlab workspace"),the desktop environment is just a fancy interface to make the underlying command-line MATLAB easier to use.

I wanted to set variables into matlab and to see them using desktop environment. In order to do it, in the workspace command-line type

desktop.

Walter +1

Thanks

[Walter Roberson]

The MATLAB Engine interface is the wrong interface for such things. The Engine interface is primarily for doing computations.

The MATLAB Automation Server might be more appropriate. See

http://www.mathworks.com/help/techdoc/matlab_external/f135590.html

[Marisol Sierra]

Hey... did you solve the problem?

[Walter Roberson]

Correction to a minor point from my 2011 posting:

i and j are not variables that exist by default. Instead, i and j are functions, just like pi and inf and nan