% support function for mmo object

function obj2 = unitaryopp(f, obj1, varargin);

    % make new memory mapped data file (blank)

    % ----------------------------------------

    newFileName = mmo.getnewfilename;

    data = memmapfile(obj1.dataFile, 'writable', obj1.writable, 'format', { 'single' obj1.dimensions 'x' });

    fid = fopen(newFileName, 'w');

    if obj1.dimensions(end) == 1, obj1.dimensions(end) = []; end

    ss.type = '()';

    ss.subs(1:length(obj1.dimensions)-1) = { ':' };

    for index = 1:obj1.dimensions(end)

        ss.subs{length(obj1.dimensions)} = index;

        tmpdata = f(subsref(data.Data.x, ss), varargin{:});

        fwrite(fid, tmpdata, 'float');

    end

    fclose(fid);    

    % copy the data

    % -------------

    obj2 = mmo(newFileName, obj1.dimensions, true, obj1.transposed);

    obj2 = updateWorkspace(obj2);