Function amd_ordering 

pub fn amd_ordering<F>(matrix: &CsrMatrix<F>) -> SparseResult<Vec<usize>>
where
    F: Float + NumAssign + Sum + SparseElement + Debug + 'static,

Approximate Minimum Degree (AMD) ordering.

Computes a fill-reducing permutation for a symmetric matrix (or the sparsity pattern A + A^T for an unsymmetric matrix). The algorithm greedily selects the node with the smallest approximate external degree at each step.

Returns a permutation vector perm such that A[perm, perm] has reduced fill during factorization.