Good use of memory - matlab

Question

If i create a cell with 1000 matrices ( size of each matrix 800*1280), clearing each matrix after using it will speed up calculations ?
Example
A=cell(1000,1);
for i=1:1000
A{i}=rand(800,1280);
end
image=A{1};
image2=A{2}; % I will use image and image2 with other functions
A{1}=[];
A{2}=[];
EDIT
The real use of the cell will be like :
A=cell(1000,1);
parfor i=1:1000
A{i}=function_that_creates_image(800,1280); % image with size 800*1280 px
end
for i=1:number_of_images % number_of_images=1000 in this case
image1=A{1};
image2=A{2};
A{1}=[];
A{2}=[];
% image1 and image 2 will be used then in the next lines
%next lines of code
end
I noticed that calculating components of A in a parfor loop is faster than calculating each component for each loop inside the for

Answer 1

If you want to use less memory and speed up calculations, it's wiser to avoid using cells. Luckily, it's very easy in your case, since all your matrices are the same size, so you could use an ND-array.
A = zeros(800,1280,1000);
for k = 1:size(A,3)
A(:,:,k) = function_that_creates_image(800,1280);
end
image = A(:,:,1);
image2 = A(:,:,2); % I will use image and image2 with other functions
EDIT:
If you want to further process each image, I would save them to a file within the parfor, so you will have 1000 .mat files at the end of the first loop:
parfor k = 1:number_of_images
A = function_that_creates_image(800,1280);
save(['images_dir\image' num2str(k) '.mat'],'A');
end
then you can load them as needed for processing using load:
for k = 1:number_of_images-1
image1 = load(['images_dir\image' num2str(k) '.mat']);
image2 = load(['images_dir\image' num2str(k+1) '.mat'];
% do what you want with those images...
end
This way you only keep 2 images in memory each time, and on the next iteration they a replaced by the next images.

Answer 2

If you fit everything in memory (you need at least 16GB to hold data and do some work on parts of it, to work on the full beast at the same time you should be having 32GB), clearing these won't change anything at all. If you don't, I would assume/hope Matlab and Windows are smart enough to optimize which chunk is held in memory and which is put on the disk, so again deleting won't help. But you might not want to rely on that.
What you can do is to have A{i} = 'path-to-file';, then load it in memory just for the time when needed. Why do you even need to first load all the images and then do work on them one by one? It would be much better for memory to simply have image1 = rand(...);, image2 = rand(...); in the loop itself, and reuse these image1 and image2. No need to even have this A.
In general, tall arrays are your memory friendly solution you should be using if you want to have tons of data at the same time. https://www.mathworks.com/help/matlab/tall-arrays.html