This solution covers several debuggers on various Linux/UNIX/Mac plaforms. For other configurations, see the Debugging section of Tech Note 1605, MEX-files Guide:
<http://www.mathworks.com/support/tech-notes/1600/1605.html>
This solution discusses the general use of a UNIX debugger followed by step-by-step examples on how to use the various UNIX debuggers.
NOTE: These examples are for illustration purposes only. For complete instructions on how to use a specific debugger, refer to the debugger's Reference Guide or help files.
The following section gives a generic description of how to debug C MEX-files. Complete instructions for each debugger follows this discussion.
1.Note: You must build your MEX-File with symbols. In order to do so, issue the following command at the MATLAB Command Prompt:
mex -g filename.c
or at the UNIX prompt:
unix> mex -g filename.c
2.At the UNIX prompt, start up MATLAB with a particular debugger
unix> matlab -D<name_of_debugger>
3.Once the debugger loads MATLAB into memory, continue running with the run command:
<debugger> run -nojvm
Note: you may have to execute the following command to load the symbols for the MEX-file:
add-sym <filename>
If you are using MATLAB older than R12 use the following instead:
<debugger> run
4.MATLAB will now start up. You can enable MEX-File debugging with
dbmex on
% call the MEX-File as you normally would
(i.e. through a MATLAB file or by its name.)
5.MATLAB will now tell you how to load the MEX-File. You can set breakpoints at this point.
<debugger> stop in mexFunction
<debugger> continue
6.Once you hit a breakpoint, you can use the debugger as you would normally.
<debugger> step
<debugger> step
7.If you are at the MATLAB prompt and want to return control to the debugger, issue the command
dbmex stop
As a rule of thumb, if you use the GCC C compiler, use the GCC debugger. If you use the native C compiler, use the native debugger.
The following is a list of available debuggers with the appropriate debugging commands noted. For a complete example on how to use these debuggers, see below:
Alpha
G-gdb run, break, step, continue, quit, print, share, file
N-dbx run, stop, step, cont, quit, print, file
HP 700
G-gdb run, break, step, continue, quit, print, share, file
N-dde DDE does not allow breakpoints to be set.
IBM RS/6000
G-gdb run, break, step, continue, quit, print, share, file
N-dbx run, stop, step, cont, quit, print, file
Linux
G-gdb run, break, step, continue, quit, print, share, file
SGI
G-gdb run, break, step, continue, quit, print, share, file
N-dbx run, stop, step, cont, quit, print, file
N-cvd CVD is not supported on the SGI at this time.
SGI64
G-gdb GCC is not supported on the SGI64 at this time.
N-dbx run, stop, step, cont, quit, print, file
N-cvd CVD is not supported on the SGI64 at this time.
Sol2
G-gdb run, break, step, continue, quit, print, file
N-dbx run, stop, step, cont, quit, print, file
Sun4
G-gdb run, break, step, continue, quit, print, add-sym, file
N-dbx run, stop, step, cont, quit, print, file
Alpha
GDB:
The following are the steps you should take to debug using GDB on the Dec Alpha:
unix> mex -g -f $MATLABROOT/bin/gccopts.sh yprime.c
($MATLABROOT is your MATLAB root directory)
unix> matlab -Dgdb
<gdb> run
dbmex on
yprime(1,1:4)
<gdb> share <full path to yprime.mexap>
i.e. /home/name/mex/yprime.mexap
<gdb>break mexFunction
<gdb> continue
<gdb> step
<gdb> break 54
<gdb> step
<gdb> continue
(This should bring you to line 54 in yprime.c)
<gdb> step
<gdb> print r2
(You should see the value of r2 printed to screen.)
<gdb> continue
(Should finish running yprime and bring you back to MATLAB.)
dbmex stop
<gdb> quit
This will display the following:
The program is running.
Quit anyway (and kill it)? (y or n)
answer y
DBX:
The following are the steps you should take to debug using DBX on the Dec Alpha:
unix> mex -g yprime.c
unix> matlab -Ddbx
<dbx> run
dbmex on
yprime(1,1:4)
<dbx> stop in mexFunction
<dbx> cont
<dbx> step
<dbx> stop at 54
<dbx> step
<dbx> cont
(This should bring you to line 54 in yprime.c)
<dbx> step
<dbx> print r2
(You should see the value of r2 printed to screen.)
<dbx> step
<dbx> cont
(Should finish running yprime and
bring you back to MATLAB.)
dbmex stop
<dbx> quit
HP700
GDB:
The GDB debugger is not supported.
DDE:
It is not possible to set breakpoints when using the DDE debugger.
IBM RS 6000
GDB:
The following are the steps you should take to debug using GDB on the IBM RS 6000:
unix> mex -g -f $MATLABRROT/bin/gccopts.sh yprime.c
($MATLABROOT is your MATLAB root directory)
unix> matlab -Dgdb
<gdb> run
dbmex on
yprime(1,1:4)
<gdb> share <full path to yprime.mexrs6>
i.e. /home/name/mex/yprime.mexrs6
<gdb> break mexFunction
<gdb> continue
<gdb> step
<gdb> break 54
<gdb> step
<gdb> continue
(This should bring you to line 54 in yprime.c)
<gdb> step
<gdb> print r2
(You should see the value of r2 printed to screen.)
<gdb> continue
(Should finish running yprime and
bring you back to MATLAB.)
dbmex stop
<gdb> quit
It will display the following:
The program is running.
Quit anyway (and kill it)? (y or n)
answer y
DBX:
The following are the steps you should take to debug using DBX on the IBM RS 6000:
unix> mex -g yprime.c
unix> matlab -Ddbx
<dbx> run
If you are using MATLAB 6.0 (R12) or R12.1, do the following instead:
<dbx> run -nojvm
dbmex on
yprime(1,1:4)
<dbx> stop in mexFunction
<dbx> cont
<dbx> step
<dbx> stop at 54
<dbx> step
<dbx> cont
(This should bring you to line 54 in yprime.c)
<dbx> step
<dbx> print r2
(You should see the value of r2 printed to screen.)
<dbx> step
<dbx> cont
(Should finish running yprime and
bring you back to MATLAB.)
dbmex stop
<dbx>quit
Linux
GDB:
The following are the steps you should take to debug using GDB on Linux:
unix> mex -g -f $MATLABROOT/bin/gccopts.sh yprime.c
($MATLABROOT is your MATLAB root directory)
unix> matlab -Dgdb
<gdb> run -nojvm
dbmex on
yprime(1,1:4)
<gdb> share <full path to yprime.mexlx>
i.e. /home/name/mex/yprime.mexlx
<gdb> break mexFunction
<gdb> continue
<gdb> step
<gdb> break 54
<gdb> step
<gdb> continue
(This should bring you to line 54 in yprime.c)
<gdb> step
<gdb> print r2
(You should see the value of r2 printed to screen.)
<gdb> continue
(Should finish running yprime and bring you back to MATLAB.)
dbmex stop
<gdb> quit
It will display the following:
The program is running.
Quit anyway (and kill it)? (y or n)
answer y
SGI
GDB:
The following are the steps you should take to debug using GDB on the SGI:
unix> mex -g -f $MATLABROOT/bin/gccopts.sh yprime.c
($MATLABROOT is your MATLAB root directory)
unix> matlab -Dgdb
<gdb> run
dbmex on
yprime(1,1:4)
<gdb> share <full path to yprime.mexsg>
i.e. /home/name/mex/yprime.mexsg
<gdb> break mexFunction
<gdb> continue
<gdb> step
<gdb> break 56
<gdb> step
<gdb> continue
(This should bring you to line 56 in yprime.c)
<gdb> step
<gdb> print r2
(You should see the value of r2 printed to screen.)
<gdb> continue
(Should finish running yprime and
bring you back to MATLAB.)
dbmex stop
<gdb> quit
It will display the following:
The program is running.
Quit anyway (and kill it)? (y or n)
answer y
DBX:
The following are the steps you should take to debug using DBX on the SGI:
unix> mex -g yprime.c
unix> matlab -Ddbx
<dbx> run
dbmex on
yprime(1,1:4)
<dbx> stop in mexFunction
<dbx> cont
<dbx> step
<dbx> stop at 54
<dbx> step
<dbx> cont
(This should bring you to line 54 in yprime.c)
<dbx> step
<dbx> print r2
(You should see the value of r2 printed to screen.)
<dbx> step
<dbx> cont
(Should finish running yprime and
bring you back to MATLAB.)
dbmex stop
<dbx>quit
CVD:
Building of MEX-files with CVD on the SGI is not supported.
SGI64
GDB:
Building of MEX-files with GDB on the SGI64 is not supported.
DBX:
The following are the steps you should take to debug using DBX on the SGI64:
unix> mex -g yprime.c
unix> matlab -Ddbx
<dbx> run
dbmex on
yprime(1,1:4)
<dbx> stop in mexFunction
<dbx> cont
<dbx> step
<dbx> stop at 54
<dbx> step
<dbx> cont
(This should bring you to line 54 in yprime.c)
<dbx> step
<dbx> print r2
(You should see the value of r2 printed to screen.)
<dbx> step
<dbx> cont
(Should finish running yprime and
bring you back to MATLAB.)
dbmex stop
<dbx>quit
CVD:
Building of MEX-files with CVD on the SGI64 is not supported.
Sol2
GDB:
The following are the steps you should take to debug uisng GDB on Solaris2:
unix> mex -g -f $MATLABROOT/bin/gccopts.sh yprime.c
($MATLABROOT is your MATLAB root directory)
unix>matlab -Dgdb
<gdb> run
dbmex on
yprime(1,1:4)
<gdb> break mexFunction
<gdb> continue
<gdb> step
<gdb> break 54
<gdb> step
<gdb> continue
(This should bring you to line 54 in yprime.c)
<gdb> step
<gdb> print r2
(You should see the value of r2 printed to screen.)
<gdb> continue
(Should finish running yprime and
bring you back to MATLAB.)
dbmex stop
<gdb> quit
It will display the following:
The program is running.
Quit anyway (and kill it)? (y or n)
answer y
DBX:
The following are the steps you should take to debug using DBX on Solaris2:
unix> mex -g yprime.c
unix> matlab -Ddbx
<dbx> run
dbmex on
yprime(1,1:4)
<dbx> stop in mexFunction
<dbx> cont
<dbx> step
<dbx> stop at 54
<dbx> step
<dbx> cont
(This should bring you to line 54 in yprime.c)
<dbx> step
<dbx> print r2
(You should see the value of r2 printed to screen.)
<dbx> step
<dbx> cont
(Should finish running yprime and
bring you back to MATLAB.)
dbmex stop
<dbx> quit
Sun4
GDB:
The following are the steps you should take to debug uisng GDB on the Sun4:
unix> mex -g -f $MATLABROOT/bin/gccopts.sh yprime.c
($MATLABROOT is your MATLAB root directory)
unix> matlab -Dgdb
<gdb> run
dbmex on
yprime(1,1:4)
<gdb> add-sym <full path to yprime.mex4> address number
i.e. (/home/name/mex/yprime.mex4)
NOTE: The debugger will tell you what the address number
is and what exactly you should type at this point.
<gdb> break mexFunction
<gdb> continue
<gdb> step
<gdb> break 54
<gdb> step
<gdb> continue
(This should bring you to line 54 in yprime.c)
<gdb> step
<gdb> print r2
(You should see the value of r2 printed to screen.)
<gdb> continue
(Should finish running yprime and
bring you back to MATLAB.)
dbmex stop
<gdb> quit
It will display the following:
The program is running.
Exit anyway? (y or n)
answer y
DBX:
The following are the steps you should take to debug using DBX on Sun4:
unix> mex -g yprime.c
unix> matlab -Ddbx
<dbx> run
dbmex on
yprime(1,1:4)
<dbx> stop in mexFunction
<dbx> cont
<dbx> step
<dbx> stop at 54
<dbx> step
<dbx> cont
(This should bring you to line 54 in yprime.c)
<dbx> step
<dbx> print r2
(You should see the value of r2 printed to screen.)
<dbx> step
<dbx> cont
(Should finish running yprime and
bring you back to MATLAB.)
dbmex stop
<dbx> quit
Mac
GDB:
The following are the steps you should take to debug using GDB on Mac:
unix> mex -g -f $MATLABROOT/bin/gccopts.sh yprime.c
unix> matlab -Dgdb
<gdb> run
dbmex on
yprime(1,1:4)
<gdb> share <full path to yprime.mexmac>
(i.e. /home/name/mex/yprime.mexmac)
<gdb> break yprime.c:mexFunction
<gdb> cont
<gdb> step
<gdb> break 54
<gdb> step
<gdb> cont
(This should bring you to line 54 in yprime.c)
<gdb> print r2
(You should see the value of r2 printed to screen.)
<gdb> cont
(Should finish running yprime and
bring you back to MATLAB.)
dbmex stop
<gdb> quit
It will display the following:
The program is running.
Exit anyway? (y or n)
answer y
