I am not able to explain that behavior. PLEASE contact technical support (link on right of my blog) with code and data to reproduce the issue. Thanks!

–Loren

I recently saw some behavior I am unable to understand given what you said above (#10).

(I’m a few years late with this comment, but since I’m using R2007a, I figured this would be a good place to post. If I’m mistaken, please let me know where this question should be asked.)

I have a function that loads some .mat files and then assigns that data to a certain structure format and then returns the new structure. Essentially, the function looks like this:

function out1 = MyFunc(path);

files = dir(path);
for fdex=3:size(files,1) %skip the '.' and '..' entries
    load_me = strcat(path, files(fdex).name);
    data = load(load_me); %the actual data-loading step
    struct(fdex).a = data.b;
    struct(fdex).b = data.f;
end
    out1 = struct;
end

(I realize struct and out1 are redundant variables, but the strange behavior only appears if it’s done this way.) Once the function returns, I have a variable in my main workspace. Since there are multiple files I loop through, the physical memory on my system is just about maxed (3.5G out of 4G) after the function completes. If I save and clear that variable (or clear all), the workspace is empty. However, the physical memory on my system stays unchanged (3.5G/4G). If I change the code to read:

function out1 = MyFunc(path);
...
    out1 = struct;
    clear struct
end

or if I don’t use the redundant variable:

function struct = MyFunc(path);
... %no mention of out1 anywhere
end

then the physical memory used on my computer drops (as expected) once I clear the variable.

Are you able to explain this behavior? It seems that MATLAB does not clear all the function variables when the function exits? (I’m using Windows 7 and I’ve used both Process Explorer and Task Manager to look at my system memory.)

The function workspace will be cleaned up when you exit the function so there is no need to manually clear the variables. If you have a large variable that has changed in the middle of the function and you want to do a lot more before returning from the function, clearing the large variable *may* be beneficial.

–Loren

The code was something as follows

function foo()

javaaddpath(‘\\share\cat_code\java’);

global cat;

if (cat == ‘siamese’)
fprintf(1, ‘Meow\n’);
end

end

The problem that would occur is that cat did not seemed to be picked up as a global and hence the condition was never triggered.

I eventually traced it down to the javaaddpath command, which calls javaclasspath which makes a call to “clear(‘java’)”.

Looking into the documentation :

clear java The same as clear all, but also clears the definitions of all Java classes defined by files on the Java dynamic class path

…. oh… so I just did clear all… fantastic! Just what I expected to happen when I add an entry to the Java path.

a very common mistake is using i or j as an index in a for loop. After that calculations with a complex nuumbers give often an unexpecting result.

The reason is the same like in your examplex, but you will not receive an error message, which makes this a little bit more dangerous.

Michael