Debugging Octave

Preliminaries

Since compilation of all the source from scratch can take long it is good to have a source folder where most of the source has been compiled. To do this ...

Workflow

1. Clone the repository.
2. Regenerate the scripts.
3. Configure.
4. Compile the code.
5. Start debugging.

Debugging oct-files

To debug oct-files, avoid making any optimization during compilation. Use export CXXFLAGS="-ggdb -Wall -O0" for C++ code or export CFLAGS="-ggdb -Wall -O0" for C code to suppress optimization. Compile the oct-file with the debug flag -g which enables debug symbols

mkoctfile -g file.cpp

start now the GNU debugger with octave

gdb octave

and run it

(gdb) run

Octave will start up. To load the symbol table the function needs to be executed, for example by invoking the help function

octave:1> help file

Now halt execution of Octave by typing ctrl+c, you'll see again the gdb prompt. Set now a breakpoint in the line of interest

(gdb) b file.cpp:40

by typing c the execution of octave will continue and you can run your oct-file directly or via an m-script.

octave:1> x = file(y)

the debugger will stop on the above defined line and you can start debugging according to the manual of GNU debugger.

Tools for debugging

GBD

To start Octave under gdb use the script run-octave at the top level of the source tree and run it with the command-line option -g like this

   cd /octave/build/tree
   ./run-octave -g

Most used commands

gdb documentation

Emacs

In short:

To start Octave in debug mode within emacs type

M-x gud-gdb

then change the command in the minibuffer to

Run gud-gdb (like this): /path/to/octave/source/tree/run-octave -gud

For more info use this link to the emacs manual section on debuggers operation

ddd

gui for gdb