how to preallocate large logical array

Hi

I'm trying to pre-allocate a huge logical matrix but I can't work out how to do it without creating a normal matrix then converting it (this intermediate step uses too much memory).

I've been trying A = zeros(50,50,50,50,50, 'uint8'); Which works to create one from 0-255 but I can't find what to write in the quotes to make it logical rather than numeric, and suspect there may be some kind of trick that I'm missing.

Thanks Mike

Answer 1

[Image Analyst]

A = false(numRows, numCols);  % Or can use true()

[Michael]

perfect, thanks

Answer 2

[James Tursa]

Another alternative (assumes that all of the elements are filled in downstream):

A = uninit(numRows, numCols, 'logical');

You can find uninit on the FEX here:

http://www.mathworks.com/matlabcentral/fileexchange/31362-uninit-create-an-uninitialized-variable-like-zeros-but-faster

Answer 3

[Ingrid]

I am not sure in which release it started working but at least in R2018a

 A = zeros(50,50,50,50,50, 'logical');

works.

[Image Analyst]

Or use false() as I suggested:

A = false(50, 50, 50, 50, 50);

It's a bit simpler and more direct.