You cannot increase the number of rows in a variable by using
variable(:, column) = more_data_than_before
When you have an existing array, the : index in the first position expands to 1 : size(existing_array,1) -- a definite size, and you cannot store more data than that there.
It is only when you are storing to an array that has not been initialized that you can use : and have it build the array as big as required.
You will need to use:
newdata = [(ceil(R{i,1}(j,10)/increment)*increment :increment:floor(R{i,1}(j+1,10)/increment)*increment )'; R{i,1}(j+1,10)];
R{i,1}(end+1:end+size(newdata,1), 1) = newdata;
Note that if R{i,1} has more than one column, this would put 0 in those columns in the expanded rows.
