Drawing on a m-file via the command window; possible?

Hey, so I've created an m-file but there's far too many outputs that I don't need all the time for me to be happy with. However I'd like to be able to get their values without having to tweak the m-file and reruning it.

Example code (m-file);

a = 6 * 4

b = 1 * 9

Now that would obviously output to the command window;

a = 24

b = 9

However, let's say I have 100 equations like that. I naturally don't want them all outputting to the command window everytime I run the code so I'd suppress their outputs with semicolons.

However I might want to get the value of b from the command window, and having to unsupress that part of the code and rerunning is a bit of a flaf when the code may take a couple minutes to fully run.

I seem to recall having a simulink file that output to the command window and all I needed to do was go to the command window and type the output name to get that value in the command window (so in the above example I would simply type "a" into the command window to get the output "a = 24").

So I was wondering if there was something similiar that can be done in a m-file?

Sorry for the layout of this question by the way, struggling to try and explain what I wish to do! For the same reason it's been a nightmare trying to search for a solution!

[Jan]

The longer I think about it, the less I understand the problem. Tying "a" in the command window seems to be the best solution already, when you want something like "a = 24". If clear is a problem, do not call it. Or are you talking about the difference between M-scripts and M-functions?

I do not think that there is a magic dwim command (do what I mean), such that you simply have to program the wanted output manually.

[Stephen]

The problem was (being a relative newcomer to MATLAB and having never really needed to use the workspace before) I didn't realise there was a difference between how M-scripts and M-functions stored to the workspace (i.e. I didn't realise that whilst M-scripts will store automatically, M-functions need extra code to manually store to the workspace).

This then resulted in my workspace not getting any variables stored. So when I would type say 'a', there wouldn't be a variable to look up.

Sorry for the confusion, and also for not knowing the difference between M-scripts and M-functions (I swear I'll get the hang of this MATLAB malarkey someday!).

Answer 1

[Ilham Hardy]

You might want check this:

disp(a)

HTH,IH

[Luffy]

 disp(a) doesn't work if u hv typed clear, so how is it different from just  typing a in the command window.

[Ilham Hardy]

The poster asks,

"So I was wondering if there was something similiar that can be done in a m-file?"

There you go,

disp

[Jan]

If typing clear has disadvantages, do not type it.

Answer 2

[Luffy]

 Yeah,you can do the similar think in a m-file as u did in your simulink file as    long as you haven't typed clear in the command window.

 Example:-
 ......
 ......
 a = 6*4;
 b = 1*9;
 ......
 .......
 Say the above was all in m-file and you run it and the variables are saved in workspace so you just need to type b in command window.

[TAB]

Variables will be saved in the base workspace only if they are created in m-script (not function).

If your m-file is a function file, you need to save the variables in base workspace manually using evalin() or assignin().

[Stephen]

See now when I run the script the variables don't get saved to the workspace; thus when I type say "a" in the command window all I get back is "??? Undefined function or variable 'a'."

Fairly new to MATLAB so it's probably a really basic/silly mistake, but have no idea why it isn't exporting to the workspace :s

Edit: Scrap all that, just realised what I had been doing was just a bad habbit from when I first started using MATLAB. Think I have it sorted, shall have a fiddle to see if I definatly have it!

Edit 2: Just seen TAB's post which didn't show up until after I posted. Pretty much in a nutshell what I was doing wrong I think. When I first started using MATLAB we always created m-files as functions, not plain script.

[TAB]

Probably your m-file is a function file.

After creating variable 'a' in m-file save it to base workspace manually.

Example:

a=[10 20 30];
assignin('base','a',a);

After running your m-file, type

>> a

on command window.

[Stephen]

That's brillaint, thanks a million!

Couple questions if that's ok?

1 - What does the base part do? I get the first a what you're naming the variable in the workspace and the second a is the value of the variable, but bit confused by the base part. Looked in the help file but still a bit confused. Are there multiple workspaces then with 'base' being the main one?

2 - If I wanted to save two (or more) variables to the workspace can I do so in one 'assignin'? For example if I had;

a = 4;

b = 7;

Instead of having to do;

assignin('base','a',a);
assignin('base','b',b);

Could I do something like;

assignin('base','a',a,'b',b)?

Thanks very much for the help, I do try and use the help files, etc. as much as possible but often get bogged down in the jargon. So I really appretiate people like yourself taking the time to help me learn the ropes!

[TAB]

1. Yes, there are multiple workspaces in matlab, like Base workspace, Function workspace and Global workspace. assignin() function saves the variable into the target workpsace.

See

>>doc assignin

For more details see Scripts and Functions and Base and Function Workspaces.

2. Unfortunately assignin() can save one variable at time. You can collect all your variable into a structure and save it to workspace in just one function call.

For example:

% These are the variables
a = 4;
b = 7;
c = 100;

% Collect them in one structure variable
Mystruct.a = a;
Mystruct.b = b;
Mystruct.c = c;

% Now save the structure
assignin('base','Mystruct',Mystruct);

Now on command window you can see them using

>> Mystruct.a
>> Mystruct.b
>> Mystruct.c