Thread Subject: Changing preferences from command line

any way to change/view particular preferences via command
line? Such as multithreading support on/off in R2007a?

Thanks ....

"First Name Last Name" <nospam@nospamplease.com> schrieb im Newsbeitrag
news:f9vhri$orl$1@fred.mathworks.com...
> any way to change/view particular preferences via command
> line? Such as multithreading support on/off in R2007a?
>
> Thanks ....

Hi,
for the multithreading: there are (undocumented) functions called
getNumberOfComputationalThreads and setNumberOfComputationalThreads, take a
look at the demo:
>> edit multithreadedcomputations

For other preferences: probably Yair could come up with some java call, I
don't know of some "official" way...

Titus

"Titus" <titus.edelhofer@mathworks.de> wrote in message
<fa415r$kk8$1@fred.mathworks.com>...
> For other preferences: probably Yair could come up with
some > java call, I don't know of some "official" way...


Thanks for the compliment - I couldn't resist the challenge...

* The preferences are stored in the matlab.prf text file
that's stored in the user's Matlab preferences folder
(prefdir is a built-in Matlab function):

edit(fullfile(prefdir,'matlab.prf'));

Each preference appears to be on a separate line in the
following format: <pref-name>=<pref-type><pref-value>

<pref-type> appears to be one of these:
  - 'B' => boolean/logical flag
  - 'C' => color (RGB numeric value)
  - 'F' => font (type,size,name)
  - 'I' => int16
  - 'J' => int32
  - 'R' => rectangular area
  - 'S' => string/char

examples:
  EditorShowLineNumbers=Btrue
  EditorMaxCommentWidth=I120

* You can read the preference names from this matlab.prf
file and then use the following (you-guessed-it) java calls
to get/set the values:
  - com.mathworks.services.Prefs.get<type>Pref(<pref-name>)
  -
com.mathworks.services.Prefs.set<type>Pref(<pref-name>,newValue);

<type>: one of Boolean, Color, RGBColor, Font, Integer,
Rectangle, String, Double (I believe Doubles get converted
to int32 - possibly a bitwise casting since both use 32 bits)

For example:
com.mathworks.services.Prefs.getBooleanPref('LayoutSnapToGrid')
com.mathworks.services.Prefs.getIntegerPref('GeneralNumComputationalThreads')

adding a second argument to get<type>Pref() appears to
indicate a default value that is returned if <pref-name> is
invalid:
com.mathworks.services.Prefs.getIntegerPref('xxxx',123)
=> 123

* STRONG WARNING: all this relies on a lot of guesswork,
trial-&-error and some common sense. It's absolutely
undocumented, unsupported and discouraged by MathWorks.
You're pretty safe as long as you stick to read-only mode.
But if you try modifying system values this way, well it
might blow in your face if you try it at home or on a system
even slightly different than the one I have (WinXP, 2007a).
Don't come crying if your Matlab prefs get all screwed up...

Yair Altman
http://ymasoftware.com

> <pref-type> appears to be one of these:
> - 'J' => int32
>
com.mathworks.services.Prefs.set<type>Pref(<pref-name>,newValue);
> <type>: one of Boolean, Color, RGBColor, Font, Integer,
> Rectangle, String, Double (I believe Doubles get converted
> to int32 - possibly a bitwise casting since both use 32 bits)

Small correction: doubles get stored in 8 bytes (=64 bits)
so either the 'J' <pref-type> is actually an int64 (not
int32), or some other conversion takes place for doubles
that I am not aware of.

Yair Altman
http://ymasoftware.com

Yair
Many, many thanks for this clear & concise explanation. It
was exactly what I was looking for. Im running two instances
of Matlab and using it to set a different background color
in each. Using these java calls on the preferences has got
me tantalisingly close to a solution ... maybe I could ask
your expert advice to get to completion?

This is the code im using:
% dont use system color
com.mathworks.services.Prefs.setBooleanPref('ColorsUseSystem',0);
% use specified color
com.mathworks.services.Prefs.setColorPref('ColorsBackground',<whatever>)

where <whatever> is a java.awt.Color object returned by
com.mathworks.services.Prefs.getColorPref('ColorsBackground')

My problem now is that the new color (or preference) does
not take effect on the desktop immediately. Instead, it
comes into effect either after a restart of Matlab or if I
open the Preferences dialog manually and then push 'Apply'.

So a quick 'n dirty solution is to use:

preferences('Colors') this opens the dialog box and then
requires the user to push 'ok' or 'Apply'. It gets the job
done, but not as elegantly as I would like.

I would like to either
1) Call the code behind the Apply button in the Preferences
dialog; or
2) Force matlab to pick up the new preferences as it would
at startup; or
3) 'refresh' the desktop

If anyone can shed light on any of these approaches I would
be most grateful. Im using R2007b,
many thanks
Ben

ps: For anyone else that's playing with this: I dont advise
trying to edit the matlab.prf via matlab(!). I created a
situation that made Matlab unworkable. I did find that
deleting the matlab.prf completely (in frustration) solved it.