Error writing to output stream

[neuromusic]

I'm getting an error when trying to run the example matlab kernel notebook:

Looking more closely, it actually toggles back and forth between displaying the expected output and throwing "error writing to output stream"

That is, if I execute the cell that has a = [1,2,3] again, it will display the expected output. A third time and it says "Error writing to output stream". A fourth time and it is fine. Etc, etc. Same for the cell that says disp(b). Nothing weird for the cells which display figs.

[neuromusic]

OK, it actually looks like the "error writing to output stream" is a Matlab error and might be a bug w/ 2014a (which is what I'm running).

http://help.mworks-project.org/discussions/problems/117-matlab-window-issue

Let me see if running a different version of Matlab fixes the problem.

[neuromusic]

Problem persists with 2011a.

[blink1073]

Hmm, I tried running the notebook again and I'm not seeing the error. Are you able to run the following from an IPython prompt:

from pymatbridge import Matlab
m = Matlab()
m.start()
m.run_code('a=[1,2,3,4]')

[neuromusic]

I have no problem running pymatbridge. That code returns the expected

{u'content': {u'code': u'a = [1,2,3,4]',
  u'datadir': u'/tmp/MatlabData/',
  u'figures': [],
  u'stdout': u'\na =\n\n     1     2     3     4\n\n'},
 u'success': u'true'}

A few updates:

• problem persists with R2015a
• restarting the kernel (via Kernel > Restart) fixes the problem
• after restarting the kernel, the PNGs are larger & higher resolution (like the ones in the example notebook versus the tiny pixelated figure in the image I posted)
• if I create a copy (via File > Make a Copy...) the new notebook works fine.

so this problem is specific to the first kernel launched.

if I restart the server then try to run the pymatbridge code you noted, the problem pops up w/ pymatbridge.

print mlab.run_code('a = [1,2,3,4]')
print mlab.run_code('a = [1,2,3,4]')
print mlab.run_code('a = [1,2,3,4]')
print mlab.run_code('a = [1,2,3,4]')

returns

{u'content': {u'datadir': u'/tmp/MatlabData/', u'code': u'a = [1,2,3,4]', u'figures': [], u'stdout': u'\na =\n\n     1     2     3     4\n\n'}, u'success': u'true'}
{u'content': {u'code': u'a = [1,2,3,4]', u'stdout': u'Error writing to output stream.\n\n'}, u'success': u'false'}
{u'content': {u'datadir': u'/tmp/MatlabData/', u'code': u'a = [1,2,3,4]', u'figures': [], u'stdout': u'\na =\n\n     1     2     3     4\n\n'}, u'success': u'true'}
{u'content': {u'code': u'a = [1,2,3,4]', u'stdout': u'Error writing to output stream.\n\n'}, u'success': u'false'}

so this seems to be a pymatbridge issue related to (same as?) arokem/python-matlab-bridge#171

[neuromusic]

I closed this issue, but it might be a good idea to have matlab_kernel better handle the u'success': u'false' that pymatbridge returns.