Mathematics for Enzyme Reaction Kinetics and Reactor Performance. F. Xavier MalcataЧитать онлайн книгу.
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where Eq. (4.108) allows further simplification to
One may similarly write
at the expense again of the rule of transposition of a product of matrices, see Eq. (4.120); the definition of inverse as conveyed by Eq. (4.124) permits simplification of Eq. (4.162) to
(4.163)
whereas Eq. (4.108) may again be invoked to attain
Inspection of Eqs. (4.161) and (4.164) confirms compatibility with the form of Eq. (4.124), so one concludes that
(4.165)
– meaning that the inverse of AT is merely the transpose of A−1; therefore, the transpose and inverse operators can also be exchanged without affecting the final result.
Although being square is a necessary condition for invertibility of a matrix, it is far from being also a sufficient condition; in fact, the rank of (n × n) matrix A must coincide with its order, so as to guarantee existence of A−1 (to be discussed later). Under such conditions, the said square matrix is termed regular – otherwise it is termed singular; as will be seen, the associated determinant is a convenient tool to effect this distinction.
4.5.2 Block Matrix
Oftentimes, matrix A to be inverted appears as a block matrix, in agreement with Eq. (4.86) – so the question is to find its inverse, say, B, in a form consistent with Eq. (4.87); A1,1 and B1,1 will hereafter denote regular (m × m) matrices, A1,2 and B1,2 denote (m × p) matrices, A2,1 and B2,1 denote (p × m) matrices, and A2,2 and B2,2 denote regular (p × p) matrices. Under these conditions, Eq. (4.124) may be reformulated to
so Eq. (4.88) may be retrieved to allow transformation of Eq. (4.166) to
(4.167)
this is equivalent to writing
and
owing to the required equality of matrices in the two sides. Equation (4.169) may be rewritten as
(4.172)
premultiplication of both sides by
(4.173)
which is equivalent to
at the expense of Eqs. (4.24), (4.57), and (4.64). By the same token, one gets
(4.175)
from Eq. (4.170) – where premultiplication of both sides by
at the expense of Eqs. (4.24), (4.57) and (4.124); in view of the definition of identity matrix, one may rewrite Eq. (4.176)