Do NOT use ADDPATH or CD or any other messing around with the MATLAB search path just for acessing data files.
All MATLAB functions which import/export data files accept relative/absolute filenames. Using relative/absolute filenames is more robust, more efficient, and easier to debug than messing around with CD or the search path. You should use relative/absolute filenames.
For example:
P = 'D:\Shared\MATLAB\100min\BT'; % got rid of the superfluous square brackets.
S = dir(fullfile(P,'*_BTlength.mat'));
for k = 1:numel(S)
F = fullfile(S(k).folder,S(k).name);
% do whatever you want with absolute filename F, e.g.:
D = load(F)
end
See also:
