inverse of a 2x2 partitioned matrix || Mata in Stata || Econometrics || U/Grad || MPhil || PhD

* Inverse of a 2x2 partitioned
Matrix A= [A11 , A12 \ A21 , A22]
* F1 = [A11 - A12A22-1A21]-1
A-1 = [F1 , -F1A12A22-1 \
-A22-1A21F1 , A22-1(I+A21F1A12A22-1)]
* F2 = [A22 - A21A11-1A12]-1
A-1 = [A11-1(I+A12F2A21A11-1) ,
-A11-1A12F2 \
-F2 A21 A11-1 , F2 ]