Support passing a vector to the power operator on a dseries
Unlike the other arithmetic operations, power does not allow element-wise operations when passed a matrix. I.e.
ts1=dseries([1;2;3], '1999y', {'MyVar1'}, {'MyVar\_1'});
ts1/[1:3]’
ts1-[1:3]’
ts1*[1:3]’
ts1+[1:3]’are all ok. But,
ts1^[1:3]’causes an error