Fréchet derivative of a negative matrix power

ID: frechet-derivative-of-a-negative-matrix-power

For a positive integer , the negative matrix power is differentiable on the open general linear group. The Neumann series gives locally around any invertible matrix. Applying the product rule to the factors of this inverse gives the displayed Fréchet derivative. Each summand chooses one inverse factor to differentiate while keeping the others in order.
The factor order matters. Only when and commute does the sum simplify to . This is a useful example of why scalar differentiation rules for powers cannot be transferred to matrices without accounting for noncommutativity.

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