Why does program execution hang when using "pause?"

I am using Windows 10, Matlab R2016a (9.0.0.341360) 64-bit win64 Feb 11, 2016 for the Coursera Machine Learning course. A number of the example programs use the "pause" operator to allow a user to observe some output before continuing.

I have noticed that about 20% of the time, when I press enter at the "pause" section of a program, it will not proceed. I have to press ctrl-c to abort, and then restart the program.

The lower left corner says "Paused: Press any key" but when I press enter, it reports "Busy" in the lower corner and hangs forever.

If I press CTRL-C, I see it is aborting at the PAUSE line.

I usually have to restart MATLAB to get it working again.

Why would "pause" fail this way? Is this a bug or am I doing something wrong?

[dpb]

Would seem likely to be a system-dependent interaction on a particular installation, unfortunately for you, yours. Probably only help to be had here will be from TMW directly; submit a support request a www.mathworks.com although you might do a search for the symptom and see if there is a published problem report/workaround.

[Phillip Remaker]

We have about a half dozen people on the Coursera class forums with the problem, so it is not just me. Does the Academic bulk license include the ability to contact support? We have all done a number of workarounds (including writing our own pause.m functions), but I'd think there might be some interest from TMW if we can reproduce.

I hate to consume support resources as an academic user, but I may check in to see if they know about it.

[jgg]

This definitely sounds like a bug in the 2016a distribution. Contact tech support; if several people are experiencing, it can adversely affect a much wider population.

[Andreas Goser]

With bugs or anticipated bugs, please get in touch with MathWorks support, really doesn't matter what your license type is.

Answer 1

[Phillip Remaker]

I opened a case with Mathworks and they made the following suggestion:

----

I believe this is a known issue in MATLAB R2016a. Some customers have been able to resolve this issue by including a “drawnow” command immediately before the “pause” command. I would recommend attempting this workaround.

----

[Rajeev Verma]

drawnow does not work as well.

Answer 2

[Likhit]

Has anyone found a solution/patch to fix this issue? I am having the same problem, right now with my code. Drawnow and Using the Space does not seem to work well.

[Phillip Remaker]

I will write a new answer based on what was discussed at the Coursera list in April 2016

Answer 3

[sam0037]

Hi,

This is a bug which only occurs in Windows 10. Using Space key to come out of pause mode works, but if Enter key is used instead, it freezes MATLAB. Developers are aware of it and working towards a fix.Currently, the only workaround is to use the Space key instead of Enter to come out of the pause mode.

[Phillip Remaker]

Aha! Brilliant. Thanks for the tip!

[Phillip Remaker]

I am sorry to report that the problem happens with both space and enter. Any other ideas?

[Michael Harradon]

I'm seeing the same bug on Window 8, if anyone from Mathworks is tracking this.

[Nikita Kuznetsov]

I'm also experiencing the same issue on Windows 7.

[Subhobroto Choudhury]

I agree, I experience the same problem with the pause command on Matlab R2016a on a Windows 7 computer.

[xa zrma]

I have experienced this issue on my Mac OS Catalina also with R2019b

Answer 4

[Phillip Remaker]

Here is a summary of the April 2016 discussion "Pause Failure Windows 10" ( Coursera Forum ) on the closed Coursera forum for Andrew Ng's Machine Learning class:

Tom Mosher, Mentor:

Another work-around is to define your own new pause.m function, put it in the working folder with your exercise scripts, and have it use the input() command.

K. Grace Kennedy, Mentor:

The instructor is using "pause" so that you can step through sections. You could use MATLAB R2015b. But since Professor Ng has his code divided into sections, I think the best solution is to comment the pauses as you have done and use the run section buttons. Click "Run and Advance" or "Run section" to run one section at a time. This will permanently fix the script and have no effect on the grader.

[gunjan]

Great! thank you so much!