error output from python matlab engine

I'd like to get better debug info than the 'matlab function cannot be evaluated' that I currently see from a complex matlab function being run from python using the python matlab engine. Is there some way to pipe extra matlab debug output to a file and/or get more info ?

[Stephen23]

The documentation

http://www.mathworks.com/help/matlab/matlab_external/troubleshoot-matlab-errors-in-python.html

states that you should get the whole MATLAB error message from the Python Engine: "When a MATLAB® function raises an error, the MATLAB Engine for Python® stops the function and catches the exception raised by MATLAB. The engine copies the error message to a new Python exception. The engine raises the Python exception."

That page gives several examples of this.

What other information would you like?

[Jeremy Rutman]

pretty much anything beyond 'matlab function cannot be evaluated' would be great - i've been using

      out = StringIO.StringIO()
      err = StringIO.StringIO()
      retvals = matlab_engine.myfunc(image_filename, nargout=3,stdout=out,stderr=err)

   outstring = out.getvalue()
    errstring = err.getvalue()
    logging.debug('ml output:'+str(outstring)+'\n')
    logging.debug('ml err output:'+str(errstring)+'\n')

Answer 1

[Robert Snoeberger]

You could get the last uncaught exception [1] and then call getReport [2] to get the error message for that exception.

Example

>>> import matlab.engine
>>> eng = matlab.engine.start_matlab()
>>>
>>> # Do something that throws an exception...
>>>
>>> eng.eval('exception = MException.last;', nargout=0)
>>> eng.eval('getReport(exception)')

References

[1] http://www.mathworks.com/help/matlab/ref/mexception.last.html

[2] http://www.mathworks.com/help/matlab/ref/mexception.getreport.html