I'm not sure I understand your structure.
Do you have one cell array with a matrix in each element, or do you have an array of 103 cells which each contains another cell array with a certain number of matrices?
I.e. is it
my_array = cell(103,1);
my_array{1} = randn(4,4); % some matrix
my_array{2} = randn(5,5); % etc.
or
my_array = cell(103,1);
my_array{1} = cell(3,1);
my_array{1}{1} = randn(4,4); % some matrix
my_array{1}{2} = randn(5,5); % etc.
my_array{2} = cell(2,1);
my_array{2}{1} = randn(4,4); % some matrix
my_array{2}{2} = randn(5,5); % etc.
