# \[WINDOWS\] new user questions about breakpoints, command window, and Quest

**URL:** <https://psychtoolbox.discourse.group/t/windows-new-user-questions-about-breakpoints-command-window-and-quest/1592>\
**Category:** Uncategorized\
**Created:** [February 23, 2006, 8:05pm UTC](https://psychtoolbox.discourse.group/t/windows-new-user-questions-about-breakpoints-command-window-and-quest/1592 "2006-02-23T20:05:38Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![daniel0906](https://avatars.discourse-cdn.com/v4/letter/d/e47774/32.png) [@daniel0906](https://psychtoolbox.discourse.group/u/daniel0906)\
**Post date:** [February 23, 2006, 8:05pm UTC](https://psychtoolbox.discourse.group/t/windows-new-user-questions-about-breakpoints-command-window-and-quest/1592/1 "2006-02-23T20:05:38Z")

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Boquan,  
  
A descriptive subject, including which Psychtoolbox platform you are  
using, is appreciated as well as your full name and  
university/research group affiliation.  
  
Quick responses to your questions:  
  
a. Do you have "clear all" at the top of your program? I believe  
that "clear all" clears breakpoints as well as variables in the  
workspace. (Maybe just change it to "clear" or check its use  
description with "help clear".)  
  
b. How do you physically switch from an active Psychtoolbox screen to  
the command window? Alt-Tab?  
  
c. If you attach or include the \_shortest\_ version of your modified  
QuestDemo.m code that produces the error you describe, then those more  
familiar with the details of using Quest can run it themselves and  
will be more likely to offer advice.  
  
Daniel Shima  
Vanderbilt Vision Research Center  
  
  

> On 2/23/06, [dingbq@...](mailto:dingbq@...) \<[dingbq@...](mailto:dingbq@...)\> wrote:  
> \> Hi all,  
> \>  
> \> I am a newbie to the psychtoolbox. I have met with the following  
> \> difficulties/questions:  
> \>  
> \> a) Does it support debugging in Matlab on PC? I have set breakpoints and  
> \> found breakpoints were erased by psychtoolbox and basically they have no  
> \> effects.  
> \>  
> \> b) During Psychphysics experiments, I have switched back to Matlab  
> \> command line to check output results, but then how to switch back to  
> \> Psychtoolbox Screen? I was never able to switch back, every time I ended up  
> \> with kill the Matlab session.  
> \>  
> \> c) In the Quest functions, do they have a valid range for "tTest",  
> \> which is a variable in the QuestDemo? I have tried to manually set the tTest  
> \> to be -10, because my experiment needs half of the time 10^tTest = 0, (I am  
> \> using tTest as in log-scale, so for real value to drive the intensity of my  
> \> stimuli, I use 10^tTest. Half of the time I want to set my intensity to be  
> \> 0, so I manually set tTest to be -10, or -100, etc. However, QuestUpdate  
> \> does not allow out-of-range values; it always generate the following error  
> \> message:  
> \>  
> \> ??? Function 'strcmp' is not defined for values of class 'struct'.  
> \>  
> \> Error in ==\> strcmp at 24  
> \>  
> \> [varargout{1:nargout}] = builtin('strcmp', varargin{:});  
> \>  
> \> Error in ==\> QuestUpdate at 34  
> \> if  
> \> strcmp(oldWarning,'backtrace')  
> \>  
> \> Error in ==\> FindPsychmetricThreshold at 133  
> \>  
> \> q=QuestUpdate(q,tTest,response);  
> \>  
> \> I want to debug, but Matlab on PC with Psychtoolbox does not allow me to  
> \> debug…  
> \>  
> \> Could you please help me out?  
> \>  
> \> Thanks a lot for your help!  
> \> Boquan.  
> \>  
> \>  
> \>  
> \> Post your message to: [psychtoolbox@yahoogroups.com](mailto:psychtoolbox@yahoogroups.com)  
> \> Please indicate OS9, OSX, or WIN version, and include your full name.  
> \> Denis Pelli, David Brainard, and Allen Ingling.  
> \> [http://psychtoolbox.org](http://psychtoolbox.org)  
> \>  
> \> Yahoo! Groups Links  
> \>  
> \>  
> \>  
> \>  
> \>  
> \>