MATLAB: Global variables in functions

functionsglobal variable

I have been trying to use global variables so I can make changes to the said variable in different functions but I can't seem to do it. It seems like the second function does not work. Please help.

    function one=new1()
clc
clear global
global m
m=0;
disp('soup')
function hamburger=eat()
m=m+1
disp('sandwich')

Best Answer

Get rid of the "clear global" function in new1(), which blew away your existing globals, and add "global m" to eat():

function one=new1()
global m
clc
m=0;
disp('soup')
function hamburger=eat()
global m
m=m+1
disp('sandwich')

And the variables are only global for the functions that actually have the "global m" line in them, not to other functions that don't have that line.

See the FAQ on globals: http://matlab.wikia.com/wiki/FAQ#Are_global_variables_bad.3F

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MATLAB: How to read global variables

The problem is not connected with your use of a global variable. I think there are two possibilities:

If you click in the figure window, but not on the button, waitforbuttonpress will return, but nothing will have been assigned to answer . In this case, answer will be empty and you will see the error.
I think it is possible that waitforbuttonpress can return before the callback function has run. The following code will then get an empty value for answer and you will see the error. The next time through, answer will have received a value.

Your description and my tests indicate that it's the second of these; more time with the documentation might support the hypothesis.

Either way the solution is this. Replace the call to waitforbuttonpress with

uiwait;

Remove if w == 0 and the corresponding end .

Insert into the callback function as the final statement before end

uiresume;

Then the progress of the main script is tied in properly with the execution of the callback function.

MATLAB: How to see global variable in workspace

You need to declare it before you need to use it inside the function where you need to use it.

It looks like p is in your workspace but that might be a different p. Did you use or create a p before you called the global line? The warnings you see tell you that if you use global, it should be the first line in your function. So somehow I think your p is not the global one you thought, but is instead a local p. Is your global p a table or cell array. What does this show:

whos p

Are you stopped at a breakpoint? I think that workspace is not the one corresponding to the code. For example in your code is a variable SoilTypeState but that does not show up in your workspace panel so the workspace panel doesn't seem like it corresponds to the code you are showing, so that's why I think maybe you're stopped at a breakpoint in a different function and then just scrolled down past that to line 325.

Best Answer

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MATLAB: How to read global variables

MATLAB: How to see global variable in workspace

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