Easily store and retrieve subsets on big matrices on disk

Stores columns of a matrix one at a time in hard disk and permits to easily recover subsets of it.

% SimpleSequence class
% ---------------------
% Permits to store big sequences of real matrices into the hard disk
% and to retrieve the data easily.
% Quick and dirty, but may be useful to you..
% Example Usage : small test
%-----------------------------
% M = 1024;
% N = 4096;
% test_data = single(randn(M,N));
%
% file = SimpleSequence('filename',M); %create object
% for n = 1:N
% file.append(test_data(:,n)); % append data, one at a time
% end
% file.close(); %close object
%
% %Retrieve all data
% data = file.get(Inf,Inf); %retrieve all data
% fprintf('Error is %f\n',norm(test_data - data))%

% % Retrieve a subsampling of the lines of data
% data_sub_lines = file.get(1:3:M,Inf);
%
% % Retrieve a subsampling of the columns of data
% data_sub_cols = file.get(Inf,1:3:N);