Debugging on UNIX :: Creating Fortran MEX-Files (External Interfaces)

External Interfaces

Debugging on UNIX

You must start MATLAB from within a debugger. To do this, specify the name of the debugger you want to use with the -D option when starting MATLAB. For example, to use dbx, the UNIX debugger, type

```
matlab -Ddbx
```

Once the debugger loads MATLAB into memory, you can start it by issuing a run command. Now, from within MATLAB, enable MEX-file debugging by typing

```
dbmex on
```

at the MATLAB prompt. Then run the MEX-file you want to debug as you would ordinarily (either directly or by means of some other function or script). Before executing the MEX-file, you will be returned to the debugger.

You may need to tell the debugger where the MEX-file was loaded or the name of the MEX-file, in which case MATLAB will display the appropriate command for you to use. At this point, you are ready to start debugging. You can list the source code for your MEX-file and set break points in it. It is often convenient to set one at mexFunction so that you stop at the beginning of the gateway routine.

Note The name mexFunction may be slightly altered by the compiler (i.e., it may have an underscore appended). To determine how this symbol appears in a given MEX-file, use the UNIX command

nm <MEX-file> | grep -i mexfunction

To proceed from the breakpoint, issue a continue command to the debugger.

Once you hit one of your breakpoints, you can make full use of any facilities your debugger provides to examine variables, display memory, or inspect registers. Refer to the documentation provided with your debugger for information on its use.

If you are at the MATLAB prompt and want to return control to the debugger, you can issue the command

```
dbmex stop
```

which allows you to gain access to the debugger so you can set additional breakpoints or examine source code. To resume execution, issue a continue command to the debugger.

Debugging Fortran Language MEX-Files Debugging on Windows