where bra–ket notation has been used for the one-dimensional projections onto the subspaces spanned by individual basis vectors. The sequence of absolute values of the entries of a in decreasing order is called the decreasing rearrangement of a. The decreasing rearrangement can be denoted μ(n,a), n = 0, 1, 2, ... Note that it is identical to the singular values of the operator diag(a). Another notation for the decreasing rearrangement is a*.
