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Federico Poloni
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You don't need to search for complicated counterexamples; just consider: the matrix with all elements equal to 1.

  • the matrix with all elements equal to 1
  • the matrix with ones in the upper triangular part and 0 in the lower triangular part.

[EDIT: removed a second counterexample after a comment pointed out it was reducible. If you want an example with all distinct eigenvalues, you can take the cyclic shift matrix.]

You don't need to search for complicated counterexamples; just consider:

  • the matrix with all elements equal to 1
  • the matrix with ones in the upper triangular part and 0 in the lower triangular part.

You don't need to search for complicated counterexamples; just consider the matrix with all elements equal to 1.

[EDIT: removed a second counterexample after a comment pointed out it was reducible. If you want an example with all distinct eigenvalues, you can take the cyclic shift matrix.]

Source Link
Federico Poloni
  • 20.2k
  • 2
  • 82
  • 120

You don't need to search for complicated counterexamples; just consider:

  • the matrix with all elements equal to 1
  • the matrix with ones in the upper triangular part and 0 in the lower triangular part.