Using this expansion we can write ∂ ∂ f ∂ ∂ A : T = d d α α [ α α 3 det ( A ) ( 1 α α 3 + I 1 ( A − − 1 ⋅ ⋅ T ) 1 α α 2 + I 2 ( A − − 1 ⋅ ⋅ T ) 1 α α + I 3 ( A − − 1 ⋅ ⋅ T ) ) ] | α α = 0 = det ( A ) d d α α [ 1 + I 1 ( A − − 1 ⋅ ⋅ T ) α α + I 2 ( A − − 1 ⋅ ⋅ T ) α α 2 + I 3 ( A − − 1 ⋅ ⋅ T ) α α 3 ] | α α = 0 = det ( A ) [ I 1 ( A − − 1 ⋅ ⋅ T ) + 2 I 2 ( A − − 1 ⋅ ⋅ T ) α α + 3 I 3 ( A − − 1 ⋅ ⋅ T ) α α 2 ] | α α = 0 = det ( A ) I 1 ( A − − 1 ⋅ ⋅ T ) .