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Diff — Spectral theorem

Revision #1577 → #1797 · back to history

modifiedCauchy: real symmetric matrices are diagonalizable2fe9b30d4b08
FieldFrom #1577To #1797
mathlib.match_kindspecial_casegeneralization
noteMathlib's spectral theorem unitarily diagonalizes any Hermitian matrix over an RCLike field; real symmetric matrices are the special case 𝕜 = ℝ.Mathlib's `Matrix.IsHermitian.spectral_theorem` unitarily diagonalizes any Hermitian matrix over an RCLike field; real symmetric matrices are the special case 𝕜 = ℝ.
modifiedHermitian condition4321fa255016
FieldFrom #1577To #1797
anchors[{"section":"Hermitian maps and Hermitian matrices","snippet":"The Hermitian condition on"},{"type":"math_alttext","value":"{\\displaystyle \\langle Ax,y\\rangle =\\langle x,Ay\\rangle .}"}]
addedFundamental theorem of algebra (used in proof)46186301d7ef
modifiedSpectral decomposition394617882454
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anchors[{"section":"Hermitian maps and Hermitian matrices","snippet":"called its spectral decomposition"},{"type":"math_alttext","value":"{\\displaystyle V_{\\lambda }=\\{v\\in V:Av=\\lambda v\\}}"}]
mathlib.match_kindspecial_caseexact
modifiedEigenspaced229f4d67e4d
FieldFrom #1577To #1797
anchors[{"section":"Hermitian maps and Hermitian matrices","snippet":"be the eigenspace corresponding to an eigenvalue"},{"type":"math_alttext","value":"{\\displaystyle V_{\\lambda }=\\{v\\in V:Av=\\lambda v\\}}"}]
modifiedNormal operator5fb0461ca161
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mathlib.moduleMathlib.Algebra.Star.BasicMathlib.Algebra.Star.SelfAdjoint
modifiedMultiplication by t with no eigenvectorsdb166985c77c
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anchors[{"section":"Possible absence of eigenvectors","snippet":"let A be the operator of multiplication by t"},{"type":"math_alttext","value":"{\\displaystyle [Af](t)=tf(t).}"}]
modifiedProjection-valued measure formulation1d50c204f37f
FieldFrom #1577To #1797
anchors[{"section":"Spectral subspaces and projection-valued measures","snippet":"One formulation of the spectral theorem expresses the operator A as an integral"},{"type":"math_alttext","value":"{\\displaystyle A=\\int _{\\sigma (A)}\\lambda \\,d\\pi (\\lambda ).}"}]
addedOperator norm equals magnitude of largest eigenvalue7dc75dd755f0
modifiedDirect integral Hilbert space02cc1e500a97
FieldFrom #1577To #1797
anchors[{"section":"Direct integrals","snippet":"We then form the direct integral Hilbert space"},{"type":"math_alttext","value":"{\\displaystyle \\int _{\\mathbf {R} }^{\\oplus }H_{\\lambda }\\,d\\mu (\\lambda ).}"}]
modifiedFunctional calculus88bcb6018336
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anchors[{"section":"Functional calculus","snippet":"the idea of defining a functional calculus"},{"type":"math_alttext","value":"{\\displaystyle [f(A)s](\\lambda )=f(\\lambda )s(\\lambda ).}"}]