... as1
for \( A= \left[\begin{array}{ccc} a_{11} & a_{12} & 0 \\ a_{21} & a_{22} & a_{23} \\ 0 & a_{32} & a_{33} \end{array} \right], \) \( A_{22}^{-1} = \frac{ a_{11} a_{33} } { a_{11} a_{22} a_{33} - a_{11} a_{23} a_{32} - a_{33} a_{12} a_{21} } \) 
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... condition,2
corrected May 12, 2005 
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...eqJ1), 3
The result, real or imaginary part, depends on the definition. Usually it is written as $2e \; {\rm Im}\; {\rm tr}[ t G^< ]$, which may be more comfortable. 
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