qLet M be a partitioned
matrix
q
q
qA (lower) linear fractional
transformation (LFT) of M over D is defined as
q Fl(M, D):=M11+M12 D(I-M22 D)–1M21
q where D has suitable dimensions
and I-M22 D is invertible.
q
q
q
q
qSimilarly, an (upper) LFT is defined as
q Fu(M, Du):=M22+M21
Du (I-M11 Du)–1M12