Computing the Inverse of a Cubic Matrix

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Bruno Tolentino
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Be the matrix A defined by [aijk] (a matrix 2x2x2), do you know how to compute a inverse this cubic matrix?
 
First you would need to define what you mean by the inverse of a cubic matrix.
 
Is the cubic matrix (the representation of ) a 3-linear map? If so, then it is a 3-tensor. I don't think there is a notion of invertibility for k-tensors, but I am not sure.
 
The inverse of a cubic matrix is for try to solve a system of conic equation, like this:

Handwritten-style algebra: a quadratic form expanded as a11x^2 + a12xy + a21yx + a22y^2 over a 2x2 matrix, then a block system with matrix [a_ij][x^T; y] times [b_ij], giving the vector equation [a_ij] r-vector plus f-vector equals zero-vector.


I think that the solution could have the same form that quadratic formula, so, would be necessary to find the inverse the matrix A...
 
If you don't find formulas, you can try the same approach as for normal matrices: solve analytically and write the final solution in matrix form again.
I'm not sure if that works here as your problem is not linear.