Sesquilinear form #
This file defines the conversion between sesquilinear forms and matrices.
Main definitions #
Matrix.toLinearMap₂given a basis define a bilinear formMatrix.toLinearMap₂'define the bilinear form onn → RLinearMap.toMatrix₂: calculate the matrix coefficients of a bilinear formLinearMap.toMatrix₂': calculate the matrix coefficients of a bilinear form onn → R
Todos #
At the moment this is quite a literal port from Matrix.BilinearForm. Everything should be
generalized to fully semibilinear forms.
Tags #
sesquilinear_form, matrix, basis
The map from Matrix n n R to bilinear forms on n → R.
This is an auxiliary definition for the equivalence Matrix.toLinearMap₂'.
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The linear map from sesquilinear forms to Matrix n m R given an n-indexed basis for M₁
and an m-indexed basis for M₂.
This is an auxiliary definition for the equivalence Matrix.toLinearMapₛₗ₂'.
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Bilinear forms over n → R #
This section deals with the conversion between matrices and sesquilinear forms on n → R.
The linear equivalence between sesquilinear forms and n × m matrices
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The linear equivalence between bilinear forms and n × m matrices
Equations
- LinearMap.toMatrix₂' = LinearMap.toMatrixₛₗ₂'
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The linear equivalence between n × n matrices and sesquilinear forms on n → R
Equations
- Matrix.toLinearMapₛₗ₂' σ₁ σ₂ = LinearEquiv.symm LinearMap.toMatrixₛₗ₂'
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The linear equivalence between n × n matrices and bilinear forms on n → R
Equations
- Matrix.toLinearMap₂' = LinearEquiv.symm LinearMap.toMatrix₂'
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Bilinear forms over arbitrary vector spaces #
This section deals with the conversion between matrices and bilinear forms on a module with a fixed basis.
LinearMap.toMatrix₂ b₁ b₂ is the equivalence between R-bilinear forms on M and
n-by-m matrices with entries in R, if b₁ and b₂ are R-bases for M₁ and M₂,
respectively.
Equations
- LinearMap.toMatrix₂ b₁ b₂ = LinearEquiv.trans (LinearEquiv.arrowCongr (Basis.equivFun b₁) (LinearEquiv.arrowCongr (Basis.equivFun b₂) (LinearEquiv.refl R R))) LinearMap.toMatrix₂'
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Matrix.toLinearMap₂ b₁ b₂ is the equivalence between R-bilinear forms on M and
n-by-m matrices with entries in R, if b₁ and b₂ are R-bases for M₁ and M₂,
respectively; this is the reverse direction of LinearMap.toMatrix₂ b₁ b₂.
Equations
- Matrix.toLinearMap₂ b₁ b₂ = LinearEquiv.symm (LinearMap.toMatrix₂ b₁ b₂)
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Adjoint pairs #
The condition for the matrices A, A' to be an adjoint pair with respect to the square
matrices J, J₃.
Equations
- Matrix.IsAdjointPair J J' A A' = (Matrix.transpose A * J' = J * A')
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The condition for a square matrix A to be self-adjoint with respect to the square matrix
J.
Equations
- Matrix.IsSelfAdjoint J A₁ = Matrix.IsAdjointPair J J A₁ A₁
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The condition for a square matrix A to be skew-adjoint with respect to the square matrix
J.
Equations
- Matrix.IsSkewAdjoint J A₁ = Matrix.IsAdjointPair J J A₁ (-A₁)
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The submodule of pair-self-adjoint matrices with respect to bilinear forms corresponding to
given matrices J, J₂.
Equations
- pairSelfAdjointMatricesSubmodule J J₂ = Submodule.map (↑LinearMap.toMatrix') (LinearMap.isPairSelfAdjointSubmodule (Matrix.toLinearMap₂' J) (Matrix.toLinearMap₂' J₂))
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The submodule of self-adjoint matrices with respect to the bilinear form corresponding to
the matrix J.
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The submodule of skew-adjoint matrices with respect to the bilinear form corresponding to
the matrix J.