reltime is of class uint32, as shown here:
load Foveal
T = ans;
class(T.reltime)
An unsigned integer cannot be negative. If you want to allow negative values use a different type such as a signed integer or a floating-point (such as single or double). Here I'll make reltime into a double:
T.reltime = double(T.reltime);
And then run the rest of the code:
T_1002 = T(matches(T.message,'1002'),:);
T_ENDSACC = T(matches(T.message,'ENDSACC'),:);
[x1 ~] = size(T_ENDSACC);
[x2 ~] = size(T_1002);
T_diff = zeros(x1,x2);
for q = 1:x1
T_diff(q,:) = T_ENDSACC.reltime(q) - T_1002.reltime(:);
end
T_diff
