See if this does what you want:
descr = {'A','B','C','A','B'};
value = [2,4,6,-5,8];
[Uv,~,ref] = unique(descr);
acc = accumarray(ref, value');
Result = table(Uv', acc)
Result =
Var1 acc
____ ___
'A' -3
'B' 12
'C' 6
The table output is optional, and just shows the result.
