>>x gives 1.598........ when x hasnt been assigned

I thought I was on a clean sheet with x,y,z default to zero

>> x

x =

1.598053182478617

>>

why do I get this?

*******************

different variable y

>> y

y =

Columns 1 through 3

-0.000000000000000 -0.024544308631620 -0.049092313081569

Columns 4 through 6

-0.073647707492896 -0.098214182642028 -0.122795424215234

Columns 7 through 9...................................... to cols 513

**************************

and again with z

>> z

z =

2.557407724654902

>>

am I not resetting correctly?

I thought that "click clear" command page would reset all?

Sorry for newbie dumb question, I dont know where to go on this

Robin

Answer 1

[Image Analyst]

Put this in the command window:

>> workspace

Now, do you see x, y, and z in the workspace panel BEFORE you type x in the command window? Yes you do. Double click on x in the workspace panel to bring it up in the variable editor. Do you see a value there? Yes. Now type x on the command line and you will see the same value.

Do you want to get rid of all variables? Do this

>> clearvars

Now when you type x it will say

Unrecognized function or variable 'x'.

Answer 2

[robin teslar]

OK so command window assignments => workspace

Clear command window doesnt clear workspace

creating a new script doc still leaves old command stuff in the workspace

so you really need to know "clearvars" assume (click clear workspace does the same thing)?

Phew

Coming from an Excel bg I expect a new worksheet to be blank but I think I can see the reasoning

what worried me is, if you had developed a long script and your vars hadnt been initialised correctly to default - I guess this becomes obvious. I am not a script kiddie obviously, dont know C

Thnx :-)

Robin

[Steven Lord]

This documentation page gives a brief description of the base workspace and function workspaces, if you're interested in more information.

[robin teslar]

Thanx for the tip

I found the link

Share Data Between Workspaces

gave examples very helpful

Just off the top of my head

could these links between variables, nests, functions, workspaces be described by a type of tree diagram? to show how a variable may or not be accesed and perhaps how it may or not be get reset or otherwise changed

(unexpectedly?)

cheers

I hope this isnt too dumb

Robin

[Image Analyst]

Robin, there is a call stack function dbstack(). But I don't think it includes what variables are in each level.

As I understand it there are (at least) 3 workspaces.

1. a "base" workspace: where variables that you declare in your scripts, or run from the command window, get put into. This will survive running/exiting your function. Running addition scripts will add their variables to this workspace.
2. a "global" workspace: where variables that you declare "global" get put into. This will survive running/exiting your function.
3. "function" workspaces: this is the workspace inside your function and when you create variables in your function, only that function can see them (unless you take extra steps to make them visible to others). Variables in this workspace get destroyed (garbage collected) once the function exist, though you can send them out via the return argument list if you need them outside that function.

[robin teslar]

Hmm, probably if id done C it would be clear and obvious

i still feel uneasy I was perticularly alarmed at this

************************

How to completely reset Matlab's workspace?

Asked by Zohar on 19 Sep 2017

Latest activity Commented on by Walter Roberson on 19 Aug 2019

259 views (last 30 days)

How can I reset Matlab's workspace (environment) as if I restarted it without actually restarting it (to avoid overhead)? Perhaps specifically to trigger garbage collection?

This is in order to resolve the problem of Matlab degrading and become slower over time, probably due to poor memory management:

https://www.mathworks.com/matlabcentral/answers/331930-can-anyone-explain-why-matlab-gets-slower-and-slower-until-restart-if-large-cell-or-struct-arrays-ar

https://groups.google.com/forum/#!topic/yalmip/VNoBeBKc9vM

3 Comments

Tim Berk on 19 Sep 2017

Isn't this exactly what

clear

does?

Adam on 19 Sep 2017

clear all

will also remove functions and classes from the cache which may further help to trigger garbage collection (for class objects). It may not though.

Zohar on 20 Sep 2017

As I mention in the second link, running the following every iteration doesn't help:

clear classes; clear functions; dbclear all; clear all; pack;

********************************

sorry about spacing, its what it does and i though easier than quoting a link

https://uk.mathworks.com/matlabcentral/answers/357286-how-to-completely-reset-matlab-s-workspace

[Image Analyst]

Robin, try this:

clc;    % Clear the command window.
clear all; % Including global variables.
close all force;  % Close all figures and GUIs (except those of imtool.)
workspace;  % Make sure the workspace panel is showing.
filebrowser;

[robin teslar]

Ok, hope you see why i went off track to start when I produced my original anomalies (started new script but not cleared workspace

coming from an Excel bg, when you start a new page everything is cleared - as expected - not so with Matlab as its angled towards scripting and you dont want your script erased unexpectedly

BTW is their an auto save feature that preserves your script?

you see from above example

*********************

clear all

will also remove functions and classes from the cache which may further help to trigger garbage collection (for class objects). It may not though.

*****************************

Its all as clear as mud

[Image Analyst]

There are a variety of options with the clear function/command. Look them up and use whichever one(s) you want.

There is an autosave function. Look at Home tab->Preferences->Editor/Debugger-> Backup files.

[Walter Roberson]

clear all does not delete graphics objects. For any given object class, it is possible for there to be a reference to a variable of that class inside one of the graphics objects. Therefore any given class might still be in use after a clear all so it is not always possible to destroy the class.

clear all also does not always deal with hardware devices, and file identifiers surive clear all

[robin teslar]

Hi IA

See how Matlab trips up the newbie

there is no drop down tab Home/preferences (unless -> has a significance i didnt find in punct

so I found it in Command fx>>preferences then I get (after a minute waiting) a conventional pop up with drop down menus

its things like this that completly stump a newbie

conventionally Home Command fx>>preferences/editor-debugger/backup files

I guess its a crossover between GUI and Command line thinking

Thanx for the tip - Ive led a sheltered life since Gui's took over from DOS

Robin

[robin teslar]

So clear needs to be used with care

As Mick Jagger said - you cant always get what you want

thanx

Robin

[Walter Roberson]

In my experience, when GUI are being discussed, the convention to indicate selection of a sub-entry or a sequence of steps some of which might only be possible on menus triggered by earlier stages, is to use -> between the parts. Using / is usually reserved for command line usage on Unix or DEC VMS systems (but not CP/M because CP/M predated hierarchy of command options)