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Fix Perron-Frobenius index nonemptiness #139

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Fix Perron-Frobenius index nonemptiness #139

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5 changes: 4 additions & 1 deletion LeanEval/LinearAlgebra/PerronFrobenius.lean
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Expand Up @@ -13,11 +13,14 @@ A Perron-Frobenius style statement for irreducible nonnegative real matrices.
Mathlib already exposes irreducibility of nonnegative matrices via `Matrix.IsIrreducible`, and
spectral radius via `spectralRadius`.
The `[Nonempty n]` assumption is necessary: for `n = Empty`, `Matrix.IsIrreducible` is vacuous,
but `Module.End.HasEigenvector` still requires a nonzero vector.
-/

@[eval_problem]
theorem irreducible_nonnegative_matrix_has_positive_eigenvector_at_spectralRadius
{n : Type*} [Fintype n] [DecidableEq n]
{n : Type*} [Fintype n] [DecidableEq n] [Nonempty n]
(A : Matrix n n ℝ)
(hA : A.IsIrreducible) :
∃ v : n → ℝ,
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