Array elements that are nilpotents
TF = isnilpotent(X, tol)
isnilpotent(X, tol) returns logical 1 (true) for array elements that are nilpotents (square to zero). This function works for quaternions and octonions (the reference below covered only the former, but the results hold for octonions).
The second parameter specifies a tolerance. If omitted the default is a small multiple of eps (see code). The tolerance parameter is ignored if X is symbolic.