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matlabworkspacemasking

Why are functions masking variables after using load inside a function?

Save this sample function as test_func.m:

function test_func
load test.mat
whos
alpha

and run this sample script:

alpha = 3;
save test.mat
test_func

Here is the output I get:

  Name       Size            Bytes  Class     Attributes

  alpha      1x1                 8  double              

??? Error using ==> alpha at 40
Not enough input arguments.

Error in ==> test_func at 4
alpha

The output of whos shows that the variable is loaded in the local workspace of the function. I can even put a breakpoint on line 4 of test_func and type alpha and I get the correct result, but as soon as I do a step forward with the debugger, it fails again: the function alpha is masking the local variable and I don't see why.

Replacing the content of test_func by

p = load('test.mat');
p.alpha

works fine but that's not what I'm trying to do. I would like to load variables directly inside the local workspace of the function.

To me it looks like a bug (I'm using Matlab R2011a) but if it's a feature can you explain it and help me find a workaround?

Solution

  • Heh, you might be right that this is a bug. Looks really strange, because the following works

    function test_func
load('test.mat','alpha');
whos
alpha

    Another thing that helps is to initialize the variable before a call to load

    function test_func
alpha = 0;
load('test.mat');
whos
alpha