How can I remove a variable from the parent workspace while a function is using it?

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I work with fairly large datasets, so the fact that they get duplicated when a function accepts them as an input can be a problem given 32bit memory constraints.
I have started using scripts instead of functions in order to save on memory usage, but this has caused additional problems, because now their is no distinction between the workspaces and I have to be very careful not to overwrite utility variables (such as x, y, t, n, etc.)
I would really like to pass a variable as a function input such that there are not two copies floating around the system.
How can I remove the variable from the parent workspace (or possibly act directly on only the parent workspace variables that are specified as functional inputs?)
Thanks, Sean

Accepted Answer

the cyclist
the cyclist on 14 Dec 2011
Are you changing the value of the variable after it is passed in? If not, then a copy is never made.
If it is changed, you could define the variable as global to ensure having only one copy.
  3 Comments
Walter Roberson
Walter Roberson on 14 Dec 2011
The only variables that can be overwritten are the ones that are initialized before the nested routines are declared.
function parent
shared1=[];
function nested1
shared1='hello'; %affects shared variable
i=15; %local variable because it was not initialized before nested routine
end
i=32; %local variable because it was not initialized before nested routine
nested1(); %will affect shared1 but not i
end

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More Answers (1)

Walter Roberson
Walter Roberson on 14 Dec 2011
To answer the original question:
evalin('caller', ['clear ', inputname(3)])
where the 3 here should be changed to the parameter number of the variable in the calling sequence.
Crashes due to doing this would not surprise me.
  1 Comment
Sean
Sean on 14 Dec 2011
Walter,
Thanks for the answer. I was unfamiliar with the 'evalin' command. I can see that it would work for what I was asking, but can also potentially be badly abused. :)
I would mark you as the accepted answer, but I already marked 'the cyclist' as such.
Thanks again,
Sean

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