# NearestResolution not working because screen('Resolutions') returns empty field

**URL:** <https://psychtoolbox.discourse.group/t/nearestresolution-not-working-because-screen-39-resolutions-39-returns-empty-field/754>\
**Category:** Uncategorized\
**Created:** [July 12, 2004, 2:58pm UTC](https://psychtoolbox.discourse.group/t/nearestresolution-not-working-because-screen-39-resolutions-39-returns-empty-field/754 "2004-07-12T14:58:42Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Allen\_Ingling](https://avatars.discourse-cdn.com/v4/letter/a/a183cd/32.png) [@Allen\_Ingling](https://psychtoolbox.discourse.group/u/Allen_Ingling)\
**Post date:** [July 12, 2004, 2:58pm UTC](https://psychtoolbox.discourse.group/t/nearestresolution-not-working-because-screen-39-resolutions-39-returns-empty-field/754/1 "2004-07-12T14:58:42Z")

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Hi,  
  
I don't know under which conditions this replicates, but sometimes when   
calling NearestResolution, I get the following error message (using PTB   
2.53, Mac OS 10.3.4, Classic mode)  
  

> \> ??? Error using ==\> /  
> \> Matrix dimensions must agree.  
> \> Error in ==\> x:Applications (Mac OS 9):MATLAB   
> \> 5:Toolbox:PsychToolbox\_2.53:PsychOneLiners:NearestResolution.m   
> \> (distance)  
> \> On line 93 ==\> d=d+log10(a.width/b.width)^2;  
> \> Error in ==\> x:Applications (Mac OS 9):MATLAB   
> \> 5:Toolbox:PsychToolbox\_2.53:PsychOneLiners:NearestResolution.m  
> \> On line 68 ==\> d(i)=distance(wish,res(i));

Has anybody else seen this or similar behavior?  
Best, Jochen  
  
  
====================================================  
Here is some background info  
====================================================  
  
Debugging shows that the call to screen('Resolutions') in line 62  

> \> res=Screen(screenNumber,'Resolutions'); % get a list of available   
> \> resolutions

sometimes returns empty width and height fields. On my system, if it   
happened, then it affected the last record, res(48).  
  
 mode: 10  
 name: '1280 x 1024, 76 Hz'  
 width: []  
 height: []  
 hz: 76  
 pixelSizes: [8 16 32]  
 depths: [1x3 struct]  
 resolutionDependsOnDepthMode: 1  
 valid: 0  
 safe: 0  
 recommended: 0  
 recommendNow: 0  
 default: 0  
 interlaced: 0  
  
By coincidence (?), 1280x1024 is the only resolution with   
displayModes.depthBlockCount==6 [all other resolutions have   
depthBlockCount\<=3, as tested with a quick-and-dirty C program similar   
to DisplayModesDemo()]. Furthermore, in the Monitor Control Panel, I   
get "76 Hz" and "76.1 Hz" options for the 1280x1024 resolution.  
  
I don't know whether the bug is in DisplayManager, Psychophysics   
toolbox or VideoToolbox (GetDisplayModes.c). I currently use the   
following workaround, checking for and replacing missing fields at the   
top of function d=distance(a,b) in NearestResolution.m.  
  

> \> %[...]  
> \> function d=distance(a,b)  
> \> % "a" may omit values, for which you "don't care".  
> \> % "a" has "pixelSize" field, but "b" has "pixelSizes" field.  
> \> % check for missing width or height fields, replace by values guessed   
> \> from name string  
> \> if isempty(b.width)  
> \> b.width=str2num(b.name(1:4));  
> \> end  
> \> if isempty(b.height)  
> \> xpos=findstr(b.name, 'x');  
> \> b.height=str2num(b.name(xpos+1:xpos+5));  
> \> end  
> \> %[...]