I have 3-D (60x72x29) cell arrays with numbers inside, and I want to add the rows across the 3rd dimension so that the resulting cell size should be (60x72). Is there any elegant way to do this?
The elegant way is to not use a cell array to hold multi-dimensional numeric data where each element only contains a scalar. MATLAB is optimized for dealing with multi-dimensional numeric arrays so you should convert your data to that format using cell2mat.
Once it is a multi-dimensional numeric array, you can use sum combined with the second input which specifies the dimension along which to perform the operation.
data = cell2mat(old_data);
S = sum(data, 3);
If you really need a cell array back, you can use num2cell on the result to turn it back into a cell array
C = num2cell(S);
Update
It looks like your initial data is a cell array of strings. If that's the case, you can instead use str2double convert the cell array of strings to a numeric array
data = str2double(old_data);
S = sum(data, 3);