% Example of how to write a slice at a time for a netcdf variable

% name of the netcdf file
filename = 'test.nc';

% number of elements in longitude and latitude dimensions
imax = 10;
jmax = 10;

% time origin (for units)
torigin = datenum(2000,1,1);

% the number of elements for unlimited dimensions and has the special value inf
% The dimension can also have a fixed size.
% Use the additional option 'Format','64bit' to create a netcdf file compatible 
% with the library version 3.6

nccreate(filename,'temperature','Dimensions',{'lon',imax,'lat',jmax,'time',inf});

% the dimensions time was already created in the previous call. Its size
% does not have to be repeated here.
nccreate(filename,'time','Dimensions',{'time'});

% format 31 is 'yyyy-mm-dd HH:MM:SS'
ncwriteatt(filename,'time','units',['days since ' datestr(torigin,31)]);

% loop over slices
for i = 1:31
    % create some random data (or load it from somewhere)
    data = randn(imax,jmax);

    % assume we have daily data for January 2014
    time = datenum(2014,1,1) + i-1;

    % [1 1 i] are the start indices where to write the data
    start = [1 1 i];

    % write a slice of data
    ncwrite(filename,'temperature',data,[1 1 i]);

    % write the corresponding time
    ncwrite(filename,'time',time - torigin,i);    
end
disp('You can check the file with the command "ncdump -v time -t test.nc".')